Aromatic polycarbonate resin, electrophotographic photoconductor, process cartridge, and electrophotographic image forming method and apparatus

ABSTRACT

An electrophotographic photoconductor has an electroconductive support, and a photoconductive layer formed thereon containing as an effective component an aromatic polycarbonate resin having a structural unit of formula (2) and a structural unit with charge transporting properties, each of the structural units being contained in an amount of 5 wt. % or more of the total weight of the polycarbonate resin. There is disclosed an aromatic polycarbonate resin having a structural unit of formula (1) and the structural unit of formula (2), with the relationship between the composition ratios being 0&lt;k/(k+j)&lt;1 when the composition ratio of the structural unit (1) is k and that of the structural unit (2) is j, or an aromatic polycarbonate resin having a repeat unit of formula (3). The formulas (1) to (3) are specified in the specification.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to aromatic polycarbonate resins which areuseful as the photoconductive materials for use in theelectrophotographic photoconductor and as the materials for use inelectronic devices such as organic electroluminescent (EL) device.

In addition, the present invention also relates to anelectrophotographic photoconductor comprising an electroconductivesupport and a photoconductive layer formed thereon comprising anaromatic polycarbonate resin provided with improved mechanical strength.

Further, the present invention relates to an electrophotographic imageforming method and apparatus using the above-mentionedelectrophotographic photoconductor.

Furthermore, the present invention also relates to a process cartridgein which the above-mentioned photoconductor is incorporated.

2. Discussion of Background

Conventionally known representative aromatic polycarbonate resins areobtained by allowing 2,2-bis(4-hydroxyphenyl)propane (hereinafterreferred to as bisphenol A) to react with a carbonate precursor materialsuch as phosgene or diphenylcarbonate. Such polycarbonate resins madefrom bisphenol A are used in many fields because of their excellentcharacteristics, such as high transparency, high heat resistance, highdimensional accuracy, and high mechanical strength.

For example, this kind of polycarbonate resin is intensively studied asa binder resin for use in an organic photoconductor in the field ofelectrophotography.

Recently organic photoconductors are used in many copying machines andprinters. These organic photoconductors have a layered structurecomprising a charge generation layer (CGL) and a charge transport layer(CTL) which are successively overlaid on an electroconductive support.The charge transport layer (CTL) comprises a binder resin and alow-molecular charge transport material (CTM) There are proposed manykinds of aromatic polycarbonate resins as the above-mentioned binderresins. The addition of such a low-molecular charge transport material(CTM) to the binder resin lowers the intrinsic mechanical strength ofthe binder resin, so that the CTL film becomes fragile. Because of thedecrease of mechanical strength of the CTL, the abrasion resistance,scratch resistance, and crack resistance of the photoconductor arelowered, with the result that the durability of the photoconductor isdecreased.

Although some vinyl polymers such as polyvinyl anthracene, polyvinylpyrene and poly-N-vinylcarbazole have been studied as high-molecularphotoconductive materials for forming a charge transport complex for usein the conventional organic photoconductor, such polymers are notsatisfactory from the viewpoint of photosensitivity.

In addition, high-molecular materials having charge transportingproperties have been also studied to eliminate the shortcomings of theabove-mentioned conventional layered photoconductor. For instance, thereare proposed an acrylic resin having a triphenylamine structure asreported by M. Stolka et al., in “J. Polym. Sci., vol 21, 969 (1983)”; avinyl polymer having a hydrazone structure as described in “Japan HardCopy '89 p. 67”; and polycarbonate resins having a triarylaminestructure as disclosed in U.S. Pat. Nos. 4,801,517, 4,806,443,4,806,444, 4,937,165, 4,959,288, 5,030,532, 5,034,296, and 5,080,989,and Japanese Laid-Open Patent Applications Nos. 64-9964, 3-221522,2-304456, 4-11627, 4-175337, 4-18371, 4-31404, and 4-133065. However,any materials have not yet been put to practical use.

According to the report of “Physical Review B46 6705 (1992)” by M. A.Abkowitz et al., it is confirmed that the drift mobility of ahigh-molecular weight charge transport material is lower than that of alow-molecular weight material by one figure. This report is based on thecomparison between the photoconductor comprising a low-molecular weighttetraarylbenzidine derivative dispersed in the photoconductive layer andthe one comprising a high-molecular polycarbonate having atetraarylbenzidine structure in its molecule. The reason for this hasnot been clarified, but it is suggested that the photoconductoremploying the high-molecular weight charge transport material producespoor results in terms of the photosensitivity and the residual potentialalthough the mechanical strength of the photoconductor is improved.

SUMMARY OF THE INVENTION

It is therefore a first object of the present invention to provide anaromatic polycarbonate resin with improved durability, which can serveas a high-molecular charge transport material in the organicphotoconductor.

A second object of the present invention is to provide anelectrophotographic photoconductor with high sensitivity and highdurability.

A third object of the present invention is to provide anelectrophotographic image forming method using the above-mentionedelectrophotographic photoconductor.

A fourth object of the present invention is to provide anelectrophotographic image forming apparatus using the above-mentionedelectrophotographic photoconductor.

A fifth object of the present invention is to provide anelectrophotographic process cartridge including the above-mentionedelectrophotographic photoconductor.

The first object of the present invention can be achieved by thefollowing aromatic polycarbonate resins:

An aromatic polycarbonate resin comprising a structural unit of formula(1) and a structural unit of formula (2), with the relationship betweenthe composition ratios being 0<k/(k+j)<1 when the composition ratio ofthe structural unit of formula (1) is k and that of the structural unitof formula (2) is j:

wherein R¹ and R², which may be the same or different, are each an acylgroup, an alkyl group having 1 to 6 carbon atoms, which may have asubstituent, or an aryl group which may have a substituent; and Ar¹,Ar², and Ar³ are each a substituted or unsubstituted arylene group;

wherein a and b are each independently an integer of 1 to 4; and R³ andR⁴ are each independently a halogen atom, an alkyl group having 1 to 6carbon atoms, which may have a substituent, an alkoxyl group having 1 to6 carbon atoms, which may have a substituent, or an aryl group which mayhave a substituent, and R³ and R⁴ may each be the same or different whena and b are each an integer of 2, 3 or 4.

An aromatic polycarbonate resin comprising a repeat unit of formula (3):

wherein R¹, R², R³, R⁴, Ar¹, Ar², Ar³, a, and b are the same as thosepreviously defined, and n is an integer of 2 to 5,000, which representsa degree of polymerization.

An aromatic polycarbonate resin comprising a structural unit of thefollowing formula (4) and the above-mentioned structural unit of formula(2), with the relationship between the composition ratios being0<k/(k+j)<1 when the composition ratio of the structural unit of formula(4) is k and that of the structural unit of formula (2) is j:

wherein c and d are each independently an integer of 0 to 5; R⁵ and R⁶are each independently a halogen atom, an alkyl group having 1 to 6carbon atoms, which may have a substituent, an alkoxyl group having 1 to6 carbon atoms, which may have a substituent, or an aryl group which mayhave a substituent, and R⁵ and R⁶ may each be the same or different whenc and d are each an integer of 2, 3, 4 or 5; and Ar³ is a substituted orunsubstituted arylene group.

An aromatic polycarbonate resin comprising a repeat unit of formula (5):

wherein a, b, c, d, R³, R⁴, R⁵, R⁶, and Ar³ are the same as thosepreviously defined, and n is an integer of 2 to 5,000, which representsa degree of polymerization.

An aromatic polycarbonate resin comprising the above-mentionedstructural unit of formula (1) and a structural unit of the followingformula (6), with the relationship between the composition ratios being0<k/(k+j)<1 when the composition ratio of the structural unit of formula(1) is k and that of the structural unit of formula (6) is j:

wherein R³ and R⁴ are each independently a halogen atom, an alkyl grouphaving 1 to 6 carbon atoms, which may have a substituent, an alkoxylgroup having 1 to 6 carbon atoms, which may have a substituent, or anaryl group which may have a substituent; and R⁷ and R⁸ are eachindependently a hydrogen atom, a halogen atom, an alkyl group having 1to 6 carbon atoms, which may have a substituent, an alkoxyl group having1 to 6 carbon atoms, which may have a substituent, or an aryl groupwhich may have a substituent.

An aromatic polycarbonate resin comprising a repeat unit of formula (7):

wherein R¹, R², R³, R⁴, R⁷, R⁸, Ar¹, Ar², Ar³ and n are the same asthose previously defined.

An aromatic polycarbonate resin comprising the above-mentionedstructural unit of formula (4) and the above-mentioned structural unitof formula (6), with the relationship between the composition ratiosbeing 0<k/(k+j)<1 when the composition ratio of the structural unit offormula (4) is k and that of the structural unit of formula (6) is j.

An aromatic polycarbonate resin comprising a repeat unit of formula (8):

wherein c, d, Ar³, R³, R⁴, R⁵, R⁶, R⁷, R⁸ and n are the same as thosepreviously defined.

An aromatic polycarbonate resin comprising the above-mentionedstructural unit of formula (1), and a structural unit of the followingformula (23), with the relationship between the composition ratios being0<k/(k+j)<1 when the composition ratio of the structural unit of formula(1) is k and that of the structural unit of formula (23) is j:

wherein R³ and R⁴ are each independently a halogen atom, an alkyl grouphaving 1 to 6 carbon atoms, which may have a substituent, an alkoxylgroup having 1 to 6 carbon atoms, which may have a substituent, or anaryl group which may have a substituent; and R⁹ and R¹⁰ are eachindependently a halogen atom, an alkyl group having 1 to 6 carbon atoms,which may have a substituent, an alkoxyl group having 1 to 6 carbonatoms, which may have a substituent, or an aryl group which may have asubstituent.

An aromatic polycarbonate resin comprising a repeat unit of formula(25):

wherein R¹, R², R³, R⁴, R⁹, R¹⁰, Ar¹, Ar², Ar³ and n are the same asthose previously defined.

An aromatic polycarbonate resin comprising the above-mentionedstructural unit of formula (1), and a structural unit of the followingformula (24), with the relationship between the composition ratios being0<k/(k+j)<1 when the composition ratio of the structural unit of formula(1) is k and that of the structural unit of formula (24) is j:

wherein R³ and R⁴ are each independently a halogen atom, an alkyl grouphaving 1 to 6 carbon atoms, which may have a substituent, an alkoxylgroup having 1 to 6 carbon atoms, which may have a substituent, or anaryl group which may have a substituent; and R⁹ and R¹⁰ are eachindependently a halogen atom, an alkyl group having 1 to 6 carbon atoms,which may have a substituent, an alkoxyl group having 1 to 6 carbonatoms, which may have a substituent, or an aryl group which may have asubstituent.

An aromatic polycarbonate resin comprising a repeat unit of formula(26):

wherein R¹, R², R³, R⁴, R⁹, R¹⁰, Ar¹, Ar², Ar³, and n are the same asthose previously defined.

An aromatic polycarbonate resin comprising the above-mentionedstructural unit of formula (4), and the above-mentioned structural unitof formula (23), with the relationship between the composition ratiosbeing 0<k/(k+j)<1 when the composition ratio of the structural unit offormula (4) is k and that of the structural unit of formula (23) is j.

An aromatic polycarbonate resin comprising a repeat unit of formula(27):

wherein c, d, Ar³, R³, R⁴, R⁵, R⁶, R⁹, R¹⁰, and n are the same as thosepreviously defined.

An aromatic polycarbonate resin comprising the above-mentionedstructural unit of formula (4), and the above-mentioned structural unitof formula (24), with the relationship between the composition ratiosbeing 0<k/(k+j)<1 when the composition ratio of the structural unit offormula (4) is k and that of the structural unit of formula (24) is j.

An aromatic polycarbonate resin comprising a repeat unit of formula(28):

wherein c, d, Ar³, R³, R³, R R⁶, R⁹, R¹⁰, and n are the same as thosepreviously defined.

The second object of the present invention can be achieved by anelectrophotographic photoconductor comprising an electroconductivesupport, and a photoconductive layer formed thereon comprising as aneffective component an aromatic polycarbonate resin which comprises thestructural unit of formula (2) and a structural unit with chargetransporting properties, each of the structural units being contained inan amount of 5 wt. % or more of the total weight of the polycarbonateresin:

wherein a and b are each independently an integer of 1 to 4; and R³ andR⁴ are each independently a halogen atom, an alkyl group having 1 to 6carbon atoms, which may have a substituent, an alkoxyl group having 1 to6 carbon atoms, which may have a substituent, or an aryl group which mayhave a substituent, and R³ and R⁴ may each be the same or different whena and b are each an integer of 2, 3 or 4.

It is preferable that the structural unit with charge transportingproperties be contained in an amount of 10 to 90 wt. % of the totalweight of the polycarbonate resin in the above-mentionedelectrophotographic photoconductor.

In the aforementioned electrophotographic photoconductor, the structuralunit with charge transporting properties may be represented by formula(1′):

wherein R¹¹ is a hydrogen atom, an alkyl group which may have asubstituent, or an aryl group which may have a substituent; Ar¹ and Ar²are each an arylene group which may have a substituent; and R¹² is anaryl group which may have a substituent.

The aromatic polycarbonate resin for use in the photoconductive layermay comprise a repeat unit of formula (3′):

wherein a, b, R³, R⁴, R⁴, R¹¹, R¹², Ar¹, Ar², and n are the same asthose previously defined.

Alternatively, in the electrophotographic photoconductor, the structuralunit with charge transporting properties may be the above-mentionedstructural unit of formula (1).

The aromatic polycarbonate resin for use in the photoconductive layermay comprise the previously mentioned repeat unit of formula (3).

The third object of the present invention can be achieved by anelectrophotographic image forming method comprising the steps ofcharging the surface of a photoconductor, exposing the charged surfaceof the photoconductor to a light image corresponding to an originalimage to be reproduced, thereby forming a latent electrostatic image onthe photoconductor, developing the latent electrostatic image to avisible image, transferring the visible image to an image receivingmember, cleaning the surface of the photoconductor, and quenching theresidual potential on the surface of the photoconductor, wherein thephotoconductor is any of the above-mentioned photoconductors comprisingthe aromatic polycarbonate resin.

The fourth object of the present invention can be achieved by anelectrophotographic image forming apparatus comprising a photoconductorcapable of forming a latent electrostatic image thereon, charging meansfor charging the surface of the photoconductor, light exposure means forexposing the charged surface of the photoconductor to a light imagecorresponding to an original image to be reproduced, thereby forming alatent electrostatic image on the photoconductor, development means fordeveloping the latent electrostatic image to a visible image, imagetransfer means for transferring the visible image to an image receivingmember, cleaning means for cleaning the surface of the photoconductor,and quenching means for quenching the residual potential on the surfaceof the photoconductor, wherein the photoconductor is any of theabove-mentioned photoconductors comprising the aromatic polycarbonateresin.

The fifth object of the present invention can be achieved by anelectrophotographic process cartridge comprising an electrophotographicphotoconductor capable of forming a latent electrostatic image thereon,wherein the electrophotographic photoconductor is any of theabove-mentioned photoconductors comprising the aromatic polycarbonateresin.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1 is a schematic cross-sectional view of a first example of theelectrophotographic photoconductor according to the present invention.

FIG. 2 is a schematic cross-sectional view of a second example of theelectrophotographic photoconductor according to the present invention.

FIG. 3 is a schematic cross-sectional view of a third example of theelectrophotographic photoconductor according to the present invention.

FIG. 4 is a schematic cross-sectional view of a fourth example of theelectrophotographic photoconductor according to the present invention.

FIG. 5 is a schematic cross-sectional view of a fifth example of theelectrophotographic photoconductor according to the present invention.

FIG. 6 is a schematic cross-sectional view of a sixth example of theelectrophotographic photoconductor according to the present invention.

FIGS. 7 to 10 are IR spectra of aromatic polycarbonate resins No. 1 toNo. 4 according to the present invention (measured from the cast film ofeach resin on an NaCl plate), respectively synthesized in

Examples 1-1 to 1-4

FIG. 11 is a schematic diagram in explanation of an embodiment of theelectrophotographic image forming method and apparatus according to thepresent invention.

FIG. 12 is a schematic diagram in explanation of another embodiment ofthe electrophotographic image forming method and apparatus according tothe present invention.

FIG. 13 is a schematic diagram in explanation of an example of theprocess cartridge according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The aromatic polycarbonate resin according to the present invention isprepared in the form of a copolymer resin comprising the above-mentionedstructural unit of formula (1) or (4) with charge transportingproperties, and the structural unit of formula (2), (6), (23) or (24)capable of providing the obtained resin with other properties than thecharge transporting properties, that is, the mechanical strength.Alternatively, according to the present invention, the aromaticpolycarbonate resin is in the form of an alternating copolymer resincomprising a repeat unit of formula (3), (5), (7), (8), (25), (26),(27), or (28), each having charge transporting properties and highmechanical strength.

The previously mentioned polycarbonate resins in the form of a copolymerresin and an alternating copolymer resin are provided with chargetransporting properties and high mechanical strength. Therefore, thosearomatic polycarbonate resins can exhibit satisfactory electricalcharacteristics, optical characteristics, and physical characteristicswhen used in a photoconductive layer of the electrophotographicphotoconductor.

The method of producing the above-mentioned aromatic polycarbonateresins according to the present invention will now be explained indetail.

The aromatic polycarbonate resins of the present invention can beobtained by the conventional synthesizing method, that is,polymerization of a bisphenol and a carbonic acid derivative.

To be more specific, the aromatic polycarbonate resins can be producedby ester interchange with a bisarylcarbonate compound, using at leastone kind of diol with charge transporting properties, represented by thefollowing formula (9) or (10), and at least one kind of diol representedby the following formula (11), (12), (30), or (31).

Alternatively, the polymerization of the diols with a halogenatedcarbonyl compound such as phosgene may be carried out in accordance withsolution polymerization or interfacial polymerization, or thepolymerization of the diols with a chloroformate such asbischloroformate derived from the diols.

wherein R¹ to R¹⁰, Ar¹ to Ar³, and a, b, c, and d are the same as thosepreviously defined.

In addition to phosgene, trichloromethyl chloroformate that is a dimerof phosgene, and bis(trichloromethyl)carbonate that is a trimer ofphosgene are usable as the halogenated carbonyl compounds in theabove-mentioned polymerization. Further, halogenated carbonyl compoundsderived from other halogen atoms than chlorine, for example, carbonylbromide, carbonyl iodide, and carbonyl fluoride are also employed.

Such conventional synthesis methods are described in the reference, forexample, “Handbook of Polycarbonate Resin” (issued by The Nikkan KogyoShimbun Ltd.).

Further, various kinds of copolymers, such as a random copolymer, analternating copolymer, a block copolymer, a random alternatingcopolymer, and a random block copolymer can be obtained by appropriatelyselecting the polymerization procedure.

For instance, a random copolymer comprising the structural unit offormula (1) or (4), and the structural unit of formula (2), (6), (23) or(24) can be obtained when the diol of formula (9) or (10) with chargetransporting properties and the diol of formula (11), (12), (30) or (31)are uniformly mixed prior to the condensation reaction with thephosgene. A random block copolymer can be obtained by the addition of aplurality of diols in the course of the reaction. Further, analternating copolymer comprising a repeat unit of formula (3), (5), (7),(8), (25), (26), (27) or (28) can be produced by carrying out thecondensation reaction of a bischloroformate compound derived from thediol of formula (11), (12), (30) or (31) and the diol having chargetransporting properties, represented by formula (9) or (10). In such acase, the above-mentioned alternating copolymer comprising a repeat unitof formula (3), (5), (7), (8), (25), (26), (27) or (28) can be similarlyproduced by carrying out the condensation reaction of a bischloroformatecompound derived from the diol of formula (9) or (10)-having chargetransporting properties, and the diol of formula (11), (12), (30) or(31). Further, a random alternating copolymer can be produced byemploying a plurality of bischloroformate compounds and/or diolcompounds in the course of the aforementioned condensation reaction.

The interfacial polymerization is carried out at the interface betweentwo phases of an alkaline aqueous solution of diols and an organicsolvent which is substantially incompatible with water and capable ofdissolving a polycarbonate therein in the presence of the carbonic acidderivative and a catalyst. In this case, a polycarbonate resin with anarrow molecular-weight distribution can be speedily obtained byemulsifying the reactive medium through the high-speed stirringoperation or addition of an emulsifying material.

As a base for preparing the alkaline aqueous solution of diols, therecan be employed an alkali metal and an alkaline earth metal. Specificexamples of the base include hydroxides such as sodium hydroxide,potassium hydroxide, and calcium hydroxide; and carbonates such assodium carbonate, potassium carbonate, calcium carbonate, and sodiumhydrogencarbonate. Those bases may be used alone or in combination. Ofthose bases, sodium hydroxide and potassium hydroxide are preferable. Inaddition, distilled water or deionized water are preferably employed forthe preparation of the above-mentioned alkaline aqueous solution ofdiols.

Examples of the organic solvent used in the above-mentioned interfacialpolymerization are aliphatic halogenated hydrocarbon solvents such asdichloromethane, 1,2-dichloroethane, 1,2-dichloroethylene,trichloroethane, tetrachloroethane, and dichloropropane; aromatichalogenated hydrocarbon solvents such as chlorobenzene anddichlorobenzene; and mixed solvents thereof. Further, aromatichydrocarbon solvents such as toluene, xylene, and ethylbenzene, oraliphatic hydrocarbon solvents such as hexane and cyclohexane may beadded to the above-mentioned solvents. The aliphatic halogenatedhydrocarbon solvents and aromatic halogenated hydrocarbon solvents arepreferable, and in particular, dichloromethane and chlorobenzene arepreferably employed in the present invention.

Examples of the catalyst used in the preparation of the polycarbonateresin include a tertiary amine, a quaternary ammonium salt, a tertiaryphosphine, a quaternary phosphonium salt, a nitrogen-containingheterocyclic compound and salts thereof, an iminoether and saltsthereof, and an amide-group-containing compound.

Specific examples of such catalysts are trimethylamine, triethylamine,tri-n-propylamine, tri-n-hexylamine,N,N,N′,N′-tetramethyl-1,4-tetramethylenediamine, 4-pyrrolidinopyridine,N,N′-dimethylpiperazine, N-ethylpiperidine, benzyltrimethylammoniumchloride, benzyltriethylammonium chloride, tetramethylammonium chloride,tetraethylammonium bromide, phenyltriethylammonium chloride,triethylphosphine, triphenylphosphine, diphenylbutylphosphine,tetra(hydroxymethyl)phosphonium chloride, benzyltriethylphosphoniumchloride, benzyltriphenylphosphonium chloride, 4-methylpyridine,1-methylimidazole, 1,2-dimethylimidazole, 3-methylpyridazine,4,6-dimethylpyrimidine, 1-cyclohexyl-3,5-dimethylpyrazole, and2,3,5,6-tetramethylpyrazine.

Those catalysts may be used alone or in combination. Of theabove-mentioned catalysts, the tertiary amine, in particular, a tertiaryamine having 3 to 30 carbon atoms, such as triethylamine is preferablyemployed in the present invention. Before and/or after the carbonic acidderivatives such as phosgene and bischloroformate are placed in thereaction system, any of the above-mentioned catalysts may be addedthereto.

To prevent oxidation of the diols in the alkaline aqueous solution inthe course of the polymerization reaction, an antioxidant such ashydrosulfite may be used.

The interfacial polymerization reaction is generally carried out attemperature in the range of 0 to 40° C., and terminated in severalminutes to 5 hours. It is desirable to maintain the reaction system topH 10 or more.

In the case of the solution polymerization, the diols are dissolved in aproper solvent to prepare a solution of the diols, and a deacidifyingagent is added thereto. Then, the bischloroformate compound, or phosgeneor the like is added to the above prepared mixture. In this case,tertiary amine compounds such as trimethylamine, triethylamine andtripropylamine, and pyridine can be used as the deacidifying agents.

Examples of the solvent for use in the above-mentioned solutionpolymerization are halogenated hydrocarbon solvents such asdichloromethane, dichloroethane, trichloroethane, tetrachloroethane,trichloroethylene, and chloroform; cyclic ethers such as tetrahydrofuranand dioxane; and pyridine.

The reaction temperature is generally in the range of 0 to 40° C. Inthis case, the solution polymerization is generally terminated inseveral minutes to 5 hours.

In the case where the polycarbonate resin is synthesized by the esterinterchange method, the diols and the bisarylcarbonate are mixed in thepresence of an inert gas, and the reaction is carried out at atemperature in the range of 120 to 350° C. under reduced pressure. Thepressure in the reaction system is stepwise reduced to 1 mmHg or less inorder to distill away the phenols generated during the reaction from thereaction system. The reaction is usually terminated in about one to 4hours. When necessary, the antioxidant may be added to the reactionsystem. As the bisarylcarbonate compound, diphenyl carbonate, di-p-tolylcarbonate, phenyl-p-tolyl carbonate, di-p-chlorophenyl carbonate, anddinaphthyl carbonate can be employed.

To control the molecular weight of the obtained polycarbonate resin, itis desirable to employ a terminator as a molecular weight modifier inany of the above-mentioned polymerization reactions. Consequently, asubstituent derived from the terminator may be bonded to the end of themolecule of the obtained polycarbonate resin.

As the terminator for use in the present invention, a monovalentaromatic hydroxy compound and haloformate derivatives thereof, and amonovalent carboxylic acid and halide derivatives thereof can be usedalone or in combination.

Specific examples of the monovalent aromatic hydroxy compound arephenols such as phenol, p-cresol, o-ethylphenol, p-ethylphenol,p-isopropylphenol, p-tert-butylphenol, p-cumylphenol,p-cyclohexylphenol, p-octylphenol, p-nonylphenol, 2,4-xylenol,p-methoxyphenol, p-hexyloxyphenol, p-decyloxyphenol, o-chlorophenol,m-chlorophenol, p-chlorophenol, p-bromophenol, pentabromophenol,pentachlorophenol, p-phenylphenol, p-isopropenylphenol,2,4-di(1′-methyl-1′-phenylethyl)phenol, β-naphthol, α-naphthol,p-(2′,4′,4′-trimethyl-chromanyl)phenol, and2-(4′-methoxyphenyl)-2-(4″-hydroxyphenyl)propane. In addition, alkalimetal salts and alkaline earth metal salts of the above phenols can alsobe employed. Various haloformate derivatives of the above-mentionedaromatic hydroxy compounds can be used as the terminators.

Specific examples of the monovalent carboxylic acid are aliphatic acidssuch as acetic acid, propionic acid, butyric acid, valeric acid, caproicacid, heptanic acid, caprylic acid, 2,2-dimethylpropionic acid,3-methylbutyric acid, 3,3-dimethylbutyric acid, 4-methylvaleric acid,3,3-dimethylvaleric acid, 4-methylcaproic acid, 3,5-dimethylcaproicacid, and phenoxyacetic acid; and benzoic acids such as benzoic acid,p-methylbenzoic acid, p-tert-butylbenzoic acid, p-butoxybenzoic acid,p-octyloxybenzoic acid, p-phenylbenzoic acid, p-benzylbenzoic acid, andp-chlorobenzoic acid. In addition, alkali metal salts and alkaline earthmetal salts of the above-mentioned aliphatic acids and benzoic acids canalso be employed. In addition, various halide derivatives of theabove-mentioned monovalent carboxylic acids can be employed as theterminators.

The molecular weight of the obtained aromatic polycarbonate resin can befreely controlled by adding any of the above-mentioned terminators inthe course of the polymerization reaction or prior to the polymerizationreaction.

Furthermore, the above-mentioned terminator can be used as a protectantfor the end group of the molecule of the obtained polycarbonate resin.By the addition of the terminator after completion of the polymerizationreaction, the end group of the obtained polycarbonate resin can beprotected and provided with various functions.

The above-mentioned terminators may be used alone or in combination. Ofthose terminators, the monovalent aromatic hydroxy compound ispreferable. Preferable examples of the terminators include phenol,p-tert-butylphenol, p-cumylphenol, and phenyl chloroformate.

In the present invention, it is preferable that the aromaticpolycarbonate resin thus obtained have a number-average molecular weightof 1,000 to 1,000,000, more preferably in the range of 2,000 to 500,000when expressed by the styrene-reduced value. When the molecular weightof the aromatic polycarbonate resin is within the above-mentioned range,the mechanical strength is sufficient so that occurrence of cracks inthe film can be inhibited in the course of film formation, and thesolubility of the obtained polycarbonate resin in the commonly usedsolvents is appropriate so that the increase in viscosity of theobtained resin solution can be prevented, which will improve the coatingoperation by use of the resin solution.

Furthermore, a branching agent may be added in a small amount during thepolymerization reaction in order to improve the mechanical properties ofthe obtained polycarbonate resin. Any compounds that have three or morereactive groups, which may be the same or different, selected from thegroup consisting of an aromatic hydroxyl group, a haloformate group, acarboxylic acid group, a carboxylic acid halide group, and an activehalogen atom can be used as the branching agents for use in the presentinvention.

Specific examples of the branching agents for use in the presentinvention are as follows:

-   -   phloroglucinol,    -   4,6-dimethyl-2,4,6-tris(4′-hydroxyphenyl)-2-heptene,    -   4,6-dimethyl-2,4,6-tris(4′-hydroxyphenyl)heptane,    -   1,3,5-tris(4′-hydroxyphenyl)benzene,    -   1,1,1-tris(4′-hydroxyphenyl)ethane,    -   1,1,2-tris(4′-hydroxyphenyl)propane,    -   α,α,α′-tris (4′-hydroxyphenyl)-1-ethyl-4-isopropylbenzene,    -   2,4-bis[α-methyl-α-(4′-hydroxyphenyl)ethyl]phenol,    -   2-(4′-hydroxyphenyl)-2-(2″,4″-dihydroxyphenyl)-propane,        tris(4-hydroxyphenyl)phosphine,    -   1,1,4,4-tetrakis(4′-hydroxyphenyl)cyclohexane,    -   2,2-bis[4′,4′-bis(4″-hydroxyphenyl)cyclohexyl]-propane,    -   α,α,α′,α-tetrakis (4′-hydroxyphenyl)-1,4-diethylbenzene,    -   2,2,5,5-tetrakis(4′-hydroxyphenyl)hexane,    -   1,1,2,3-tetrakis(4′-hydroxyphenyl)propane,    -   1,4-bis (4′,4″-dihydroxytriphenylmethyl)benzene,    -   3,3′,5,5′-tetrahydroxydiphenyl ether,    -   3,5-dihydroxybenzoic acid,    -   3,5-bis(chlorocarbonyloxy)benzoic acid,    -   4-hydroxyisophthalic acid,    -   4-chlorocarbonyloxyisophthalic acid,    -   5-hydroxyphthalic acid,    -   5-chlorocarbonyloxyphthalic acid,    -   trimesic trichloride, and    -   cyanuric chloride.

Those branching agents may be used alone or in combination.

The polycarbonate resin thus synthesized is purified by removing thecatalyst and the antioxidant used in the polymerization; unreacted dioland terminator; and impurities such as an inorganic salt generatedduring the polymerization. Through the above-mentioned purifyingprocedure, the polycarbonate resin can be used, for example, in thephotoconductive layer of the electrophotographic photoconductoraccording to the present invention. The previously mentioned “Handbookof Polycarbonate Resin” (issued by Nikkan Kogyo Shimbun Ltd.) can bereferred to for such a procedure for purifying the polycarbonate resin.To the aromatic polycarbonate resin produced by the previously mentionedmethods, various additives such as an antioxidant, a light stabilizer, athermal stabilizer, a lubricant, and a plasticizer can be added whennecessary.

The structural units of formulas (1) and (2), which are the basicstructural units for the preparation of the aromatic polycarbonateresins according to the present invention, will be now explained indetail.

The alkyl group mentioned in the structural units for use in the presentinvention is a straight-chain, branched, or cyclic alkyl group having 1to 6 carbon atoms. The alkyl group may have a substituent such as afluorine atom, cyano group, or a phenyl group which may have asubstituent selected from the group consisting of a halogen atom, and astraight-chain or branched, or cyclic alkyl group having 1 to 6 carbonatoms.

Specific examples of such a substituted or unsubstituted alkyl group aremethyl group, ethyl group, n-propyl group, iso-propyl group, t-butylgroup, s-butyl group, n-butyl group, iso-butyl group, trifluoromethylgroup, 2-cyanoethyl group, benzyl group, 4-chlorobenzyl group,4-methylbenzyl group, cyclopentyl group, and cyclohexyl group.

Specific examples of the substituted or unsubstituted alkoxyl groupmentioned in the structural units for use in the present invention aremethoxy group, ethoxy group, n-propoxy group, iso-propoxy group,n-butoxy group, iso-butoxy group, s-butoxy group, t-butoxy group,2-hydroxyethoxy group, 2-cyanoethoxy group, benzyloxy group,4-methylbenzyloxy group, and trifluoromethoxy group.

Examples of the acyl group represented by R¹ and R² are acetyl group,propionyl group, and benzoyl group.

Examples of the halogen atom represented by R³ to R¹⁰ are fluorine atom,chlorine atom, bromine atom, and iodine atom.

As the aryl group represented by R¹ to R¹⁰, which includes aheterocyclic group, there can be employed phenyl group, naphthyl group,biphenylyl group, terphenylyl group, pyrenyl group, fluorenyl group,9,9-dimethyl-2-fluorenyl group, azulenyl group, anthryl group,triphenylenyl group, chrysenyl group, fluorenylidene-phenyl group,5H-dibenzo[a,d]cycloheptenylidenephenyl group, thienyl group,benzothienyl group, furyl group, benzofuranyl group, carbazolyl group,pyridinyl group, pyrrolidyl group, and oxazolyl group.

The above-mentioned aryl group may have a substituent such as thepreviously mentioned substituted or unsubstituted alkyl group,substituted or unsubstituted alkoxyl group, or a halogen atom such asfluorine atom, chlorine atom, bromine atom, or iodine atom.

In addition to the above, a group represented by the following formula(13) can be employed as R¹ and R² when R¹ and R² are each a substitutedor unsubstituted aryl group:

wherein Z is —O—, —S—, —SO—, —SO₂—, —CO—, —(CH₂)_(h)—, or

-   -   in which R²¹ is a hydrogen atom, a substituted or unsubstituted        alkyl group, a substituted or unsubstituted alkoxyl group, a        halogen atom, a substituted or unsubstituted aryl group,        substituted or unsubstituted arylamino group, nitro group, or        cyano group; R²² is a hydrogen atom, a substituted or        unsubstituted alkyl group, or a substituted or unsubstituted        aryl group; h is an integer of 1 to 12; and i is an integer of 1        to 3.

In the above, as the substituted or unsubstituted arylamino group, therecan be employed an amino group having one or two substituted orunsubstituted aryl groups as the substituents.

As a substituted or unsubstituted arylene group represented by Ar¹ toAr³, there can be employed any bivalent groups derived from thesubstituted or unsubstituted aryl group as defined in the previousdescription.

The structural unit of formula (1′) will now be explained in detail.

wherein Ar¹ and Ar² are each an arylene group which may have asubstituent; R¹¹ is a hydrogen atom, an alkyl group which may have asubstituent, or an aryl group which may have a substituent; and R¹² isan aryl group which may have a substituent.

When R¹¹ is a substituted aryl group, an amino group represented by thefollowing formula (14) may be used as the substituent.

wherein R²³ and R²⁴ are each a substituted or unsubstituted alkyl groupor a substituted or unsubstituted aryl group, and R²³ and R²⁴ may form aring together or in combination with a carbon atom of the aryl group toconstitute piperidino group, morpholino group, or julolidyl group.

In formula (1′), R¹² is an aryl group which may have a substituent. Inaddition to the above-mentioned examples of aryl group, there can beemployed a monovalent group derived from a heterocyclic group having anamine structure, such as pyrrole, pyrazole, imidazole, triazole,dioxazole, indole, isoindole, benzimidazole, benzotriazole,benzisoxazine, carbazole, phenoxazine, and a group represented by thefollowing formula (15):

wherein R²⁵ and R²⁶ are each an acyl group, an alkyl group which mayhave a substituent, or an aryl group which may have a substituent; Ar⁴is an arylene group; and p is an integer of 1 to 3.

The above-mentioned groups may have a substituent such as a substitutedor unsubstituted alkyl group, a substituted or unsubstituted aryl group,or a halogen atom.

When R²⁵ and R²⁶ are each a substituted or unsubstituted aryl group, thepreviously mentioned group of formula (13) is adaptable.

Various kinds of diols have been studied to obtain an aromaticpolycarbonate resin capable of serving as a photoconductive materialwith improved mechanical durability. For instance, Japanese Laid-OpenPatent Applications 11-29634 and 11-30873 disclose aromaticpolycarbonate resins which are produced using diols having an etherskeleton and a thioether skeleton, such as 4,4′-dihydroxydiphenyl etherand 4,4′-dihydroxydiphenylsulfide. Even though such conventionalaromatic polycarbonate resins are used in the electrophotographicphotoconductor, sufficient durability cannot be obtained. In the priorart, there is no description about the effect of any substituent in thestructure of conventional diols.

The inventors of the present invention have discovered that thedurability of the polycarbonate resins comprising the structural unit offormula (2) or (6) is superior to that of the polycarbonate resins withthe conventional ether skeleton. The structural unit of formula (2) or(6) is characterized in that an ether skeleton is included, with abenzene ring having at least one substitutent. The reason why thedurability of the obtained polycarbonate resin comprising the structuralunit of formula (2) or (6) is remarkably improved has not yet beenclarified, but the substituent on the benzene ring is supposed to workas an internal plasticizer in the polymeric molecular chain. The similareffect of improving the durability can be caused by the repeat unit offormula (3), (5), (7) or (8) because the structural unit of formula (2)or (6) is included in the above-mentioned repeat unit.

Furthermore, the durability of the aromatic polycarbonate resincomprising the structural unit of formula (23) or (24) is also improvedbecause of the presence of a substituent at the o-position with respectto the ether linkage moiety. Such a mechanism is also unknown, but it issupposed that the substituent situated at the o-position with respect tothe ether linkage moiety can serve as a protectant for the ether linkagemoiety, that is, a part of the main chain, and accordingly, chemicaldeterioration can be inhibited. Owing to the presence of such asubstituent, the main chain of the polycarbonate resin can be preventedfrom being cut, whereby sufficient mechanical strength and durability ofthe obtained polycarbonate resin can be maintained. The similar effectof improving the durability can be caused by the repeat unit of formula(25), (26), (27) or (28) because the structural unit of formula (23) or(24) is included in the above-mentioned repeat unit.

In the aromatic polycarbonate resin copolymer comprising the structuralunit of formula (1) or (4) and the structural unit of formula (2), (6),(23) or (24), the amount ratio of the structural unit of formula (1) or(4) may be freely determined, but preferably 5 wt. % or more, morepreferably 10 to 90 wt. % in view of the charge transporting properties.

In the preparation of the aromatic polycarbonate resins according to thepresent invention, a diol with charge transporting properties,represented by the previously mentioned formula (9) or (10) is employed.In addition to the diol of formula (9) or (10), any conventional diolswith charge transporting properties are usable as it is in order toimprove the electrical and mechanical characteristics of the obtainedpolycarbonate resin.

Examples of the above-mentioned conventional diols with chargetransporting properties are as follows: acetophenone derivatives(Japanese Laid-Open Patent Applications 7-325409, 7-258399, 8-269183,and 9-151248), distyrylbenzene derivatives (Japanese Laid-Open PatentApplication 9-71642), diphenetylbenzene derivatives (Japanese Laid-OpenPatent Applications 9-127713 and 9-104746), α-phenylstilbene derivatives(Japanese Laid-Open Patent Applications 9-297419, 11-2909, 9-241369,9-272735, and 11-5836), butadiene derivatives (Japanese Laid-Open PatentApplications 9-80783 and 9-235367), hydrogenated butadiene derivatives(Japanese Laid-Open Patent Applications 9-80784 and 9-87376),diphenylcyclohexane derivatives (Japanese Laid-Open Patent Applications9-80772 and 9-110976), distyryltriphenylamine derivatives (JapaneseLaid-Open Patent Applications 9-222740 and 9-268226), distyryldiaminederivatives (Japanese Laid-Open Patent Applications 11-218948 and11-60718), diphenyldistyrylbenzene derivatives (Japanese Laid-OpenPatent Applications 9-265197, 9-265201, 9-221544, and 9-227669),stilbene derivatives (Japanese Laid-Open Patent Applications 9-211877,11-72937, 9-157378, and 11-71453), m-phenylenediamine derivatives(Japanese Laid-Open Patent Applications 9-304956, 9-304957, 9-302084,and 9-302085), resorcin derivatives (Japanese Laid-Open PatentApplications 9-329907 and 9-328539), and triarylamine derivatives(Japanese Laid-Open Patent Applications 64-9964, 7-199503, 8-176293,8-208820, 8-253568, 8-269446, 3-221522, 4-11627, 4-183719, 4-124163,4-320420, 4-316543, 5-310904, 7-56374, and 8-62864, and U.S. Pat. Nos.5,428,090 and 5,486,439.).

As mentioned above, the aromatic polycarbonate resin according to thepresent invention is remarkably useful as a charge transport materialwhen used in combination with a charge generation material in theelectrophotographic photoconductor, in particular, in thefunction-separating electrophotographic photoconductor. In addition tothe above, the aromatic polycarbonate resin of the present invention canbe preferably employed as electronic devices such as an organicelectroluminescent (EL) device in the field of electronics.

An electrophotographic photoconductor according to the present inventionwill now be explained in detail.

The electrophotographic photoconductor of the present inventioncomprises an electroconductive support, and a photoconductive layerformed thereon comprising as an effective component an aromaticpolycarbonate resin which comprises the above-mentioned structural unitof formula (2) and a structural unit with charge transportingproperties, each of the structural units being contained in an amount of5 wt. % or more of the total weight of the polycarbonate resin:

wherein a, b, R³, and R⁴ are the same as those previously defined.

In the electrophotographic photoconductor of the present invention, thephotoconductive layer comprises an aromatic polycarbonate resin in theform of a copolymer which comprises the structural unit of theabove-mentioned formula (2), and the structural unit with chargetransporting properties, for example, represented by the above-mentionedformula (1′) or (1), or an aromatic polycarbonate resin in the form ofan alternating copolymer comprising a repeat unit, for example,represented by the above-mentioned formula (3′) or (3). Suchpolycarbonate resins can exhibit high mechanical strength, so that thesensitivity of the obtained photoconductor is remarkably improved.

The above-mentioned polycarbonate resins for use in theelectrophotographic photoconductor of the present invention can beproduced by the previously mentioned method, using the dial of theformula (11) and the diol with charge transporting properties, such asthe dial of formula (32) or formula (10). Those diols are shown below.

wherein R³, R⁴, R⁵, R⁶, R¹¹, R¹², Ar¹, Ar², Ar³, a, and b are the sameas those previously defined.

Further, various kinds of copolymers, such as a random copolymer, analternating copolymer, a block copolymer, a random alternatingcopolymer, and a random block copolymer can be obtained by appropriatelyselecting the polymerization procedure.

For instance, a random copolymer comprising the structural unit offormula (2) and the structural unit of formula (1′) or (1) can beobtained when the diol of formula (11) and the diol of formula (32) or(10) with charge transporting properties are uniformly mixed prior tothe condensation reaction with the phosgene. A random block copolymercan be obtained by the addition of a plurality of diols in the course ofthe reaction. Further, an alternating copolymer comprising a repeat unitof formula (3′) or (3) can be produced by carrying out the condensationreaction of a bischloroformate compound derived from the diol of formula(11) and the diol having charge transporting properties, represented byformula (32) or (10). In such a case, the above-mentioned alternatingcopolymer comprising a repeat unit of formula (3) or (3′) can besimilarly produced by carrying out the condensation reaction of abischloroformate compound derived from the diol of formula (32) or (10)having charge transporting properties and the diol of formula (11).Further, a random alternating copolymer can be produced by employing aplurality of bischloroformate compounds and/or diol compounds in thecourse of the aforementioned condensation reaction.

A desired aromatic polycarbonate resin comprising at least onestructural unit of formula (2) and at least one structural unit havingcharge transporting properties such as the structural unit of formula(1′) or (1) can be provided by freely employing the diol of formula (11)in combination with the diol with charge transporting properties,represented by formula (32) or (10) In such a case, the amount ratio ofthe diol of formula (11) to the diol of formula (32) or (10) may beselected within a wide range in light of the desired characteristics ofthe obtained aromatic polycarbonate resin so that each of the structuralunit of formula (2), and the structural unit with charge transportingproperties is contained in an amount of 5 wt. % or more of the totalweight of the produced aromatic polycarbonate resin. Furthermore, it ispreferable that the structural unit with charge transporting propertiesbe contained in an amount of 10 to 90 wt. % of the total weight of thepolycarbonate resin.

The durability of the polycarbonate resin is remarkably improved byusing the diol of formula (11) as the starting material. In order tocontrol the mechanical properties of the obtained resin, the aromaticpolycarbonate resin in the form of a copolymer may further compriseother conventional structural units. In this case, the structural unitsfor use in the conventional polycarbonate resins, for example, asdescribed in the previously mentioned reference “Handbook ofPolycarbonate Resin” (issued by The Nikkan Kogyo Shimbun Ltd.) can beutilized. One of the preferable structural units for use in thepolycarbonate resin is a structural unit represented by the followingformula (33) which is conventionally known:

The starting material for the aforementioned structural unit of formula(33) is a diol represented by the following formula (34):HO—X—OH  (34)wherein X is a substituted or unsubstituted bivalent aliphatic group, asubstituted or unsubstituted bivalent cyclic aliphatic group, asubstituted or unsubstituted bivalent aromatic group, a bivalent groupprepared by bonding the aforementioned bivalent groups, or a bivalentgroup represented by formula (16), (17), or (18):

in which R²⁷, R²⁸, R²⁹, and R³⁰ are each independently an alkyl groupwhich may have a substituent, an aryl group which may have asubstituent, or a halogen atom; a and b are each independently aninteger of 0 to 4; c and d are each independently an integer of 0 to 3;and l is an integer of 0 or 1, and when l=1, Y is a straight-chainalkylene group having 2 to 12 carbon atoms, a substituted orunsubstituted branched alkylene group having 3 to 12 carbon atoms, abivalent group comprising at least one alkylene group having 1 to 10carbon atoms and at least one oxygen atom and/or sulfur atom, —O—, —S—,—SO—, —SO₂—, —CO—, —COO—,

in which Z¹ and Z² are each a substituted or unsubstituted bivalentaliphatic group, or a substituted or unsubstituted arylene group; R³¹,R³², and R³⁸ are each independently a halogen atom, a substituted orunsubstituted alkyl group, a substituted or unsubstituted alkoxyl group,or a substituted or unsubstituted aryl group; R³³, R³⁴, R³⁵, R³⁶, andR³⁷ are each independently a hydrogen atom, a halogen atom, asubstituted or unsubstituted alkyl group, a substituted or unsubstitutedalkoxyl group, or a substituted or unsubstituted aryl group, and R³² andR³³ may form together a carbon ring having 5 to 12 carbon atoms; l′ andl″ are each an integer of 0 or 1, and when l′ and l″=1, R³⁹ and R⁴⁰ areeach an alkylene group having 1 to 4 carbon atoms; R⁴¹ and R⁴² are eachindependently a substituted or unsubstituted alkyl group or asubstituted or unsubstituted aryl group; e and g are each independentlyan integer of 0 to 4; f is an integer of 1 or 2; h is an integer of 0 to20; and i is an integer of 0 to 2000.

By using such a diol of formula (34), there can be obtained a copolymerresin with improved mechanical properties. In this case, the diolsrepresented by formula (34) can be used alone or in combination in thepreviously mentioned polymerization reaction.

The above-mentioned structural unit of formula (33) will now beexplained by referring to the diol of formula (34) that is the startingmaterial for the structural unit of formula (33).

In the case where X in the diol of formula (34) represents a bivalentaliphatic group or a bivalent cyclic aliphatic group, the representativeexamples of the diol are as follows: ethylene glycol, diethylene glycol,triethylene glycol, polyethylene glycol, polytetramethylene etherglycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol,3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,5-hexanediol,1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol,1,11-undecanediol, 1,12-dodecanediol, neopentyl glycol,2-ethyl-1,6-hexanediol, 2-methyl-1,3-propanediol,2-ethyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol,1,3-cyclohexanediol, 1,4-cyclohexanediol, cyclohexane-1,4-dimethanol,2,2-bis(4-hydroxycyclohexyl)propane, xylylenediol,1,4-bis(2-hydroxyethyl)benzene, 1,4-bis(3-hydroxypropyl)benzene,1,4-bis(4-hydroxybutyl)benzene, 1,4-bis(5-hydroxypentyl)benzene,1,4-bis(6-hydroxyhexyl)benzene, and isophorone diol.

In the case where X in the diol of formula (34) represents a bivalentaromatic group, there can be employed any bivalent groups derived fromthe same substituted or unsubstituted aryl group as previously defined.

When Y in the formula (16) is a bivalent group comprising at least onealkylene group having 1 to 10 carbon atoms and at least one oxygen atomand/or sulfur atom, as mentioned above, the following specific examplescan be employed:OCH₂CH₂O,OCH₂CH₂OCH₂CH₂O,OCH₂CH₂OCH₂CH₂OCH₂CH₂O,OCH₂CH₂CH₂O,OCH₂CH₂CH₂CH₂O,OCH₂CH₂CH₂CH₂CH₂CH₂O,OCH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂O,CH₂O,CH₂CH₂O,CHE_(t)OCHE_(t)O (E_(t)=ethylene group),CHCH₃O,SCH₂OCH₂S,CH₂OCH₂,OCH₂OCH₂OSCH₂CH₂OCH₂OCH₂CH₂S,OCH₂CHCH₃OCH₂CHCH₃O,SCH₂S,SCH₂CH₂S,SCH₂CH₂CH₂S,SCH₂CH₂CH₂CH₂S,SCH₂CH₂CH₂CH₂CH₂CH₂SSCH₂CH₂SCH₂CH₂S, andSCH₂CH₂OCH₂CH₂OCH₂CH₂S.

When Y in formula (16) represents a branched alkylene group having 3 to12 carbon atoms, there can be employed as the substituent an aryl groupwhich may have a substituent or a halogen atom.

When Z¹ and Z² are each a substituted or unsubstituted bivalentaliphatic group, there can be employed any bivalent groups obtained byremoving hydroxyl group from the diol of formula (34) where X representsa bivalent aliphatic group or bivalent cyclic aliphatic group.

When Z¹ and Z² are each a substituted or unsubstituted arylene group,there can be employed any bivalent groups derived from theabove-mentioned substituted or unsubstituted aryl group.

Preferable examples of the diol of formula (34) in which X represents abivalient aromatic group are as follows:

-   bis(4-hydroxyphenyl)methane,-   bis(2-methyl-4-hydroxyphenyl)methane,-   bis(3-methyl-4-hydroxyphenyl)methane,-   1,1-bis(4-hydroxyphenyl)ethane,-   1,2-bis(4-hydroxyphenyl)ethane,-   bis(4-hydroxyphenyl)phenylmethane,-   bis(4-hydroxyphenyl)diphenylmethane,-   1,1-bis(4-hydroxyphenyl)-1-phenylethane,-   1,3-bis(4-hydroxyphenyl)-1,1-dimethylpropane,-   2,2-bis(4-hydroxyphenyl)propane,-   2-(4-hydroxyphenyl)-2-(3-hydroxyphenyl)propane,-   1,1-bis(4-hydroxyphenyl)-2-methylpropane,-   2,2-bis(4-hydroxyphenyl)butane,-   1,1-bis(4-hydroxyphenyl)-3-methylbutane,-   2,2-bis(4-hydroxyphenyl)pentane,-   2,2-bis(4-hydroxyphenyl)-4-methylpentane,-   2,2-bis(4-hydroxyphenyl)hexane,-   4,4-bis(4-hydroxyphenyl)heptane,-   2,2-bis(4-hydroxyphenyl)nonane,-   bis(3,5-dimethyl-4-hydroxyphenyl)methane,-   2,2-bis (3-methyl-4-hydroxyphenyl)propane,-   2,2-bis(3-isopropyl-4-hydroxyphenyl)propane,-   2,2-bis(3-sec-butyl-4-hydroxyphenyl)propane,-   2,2-bis(3-tert-butyl-4-hydroxyphenyl)propane,-   2,2-bis(3-cyclohexyl-4-hydroxyphenyl)propane,-   2,2-bis(3-allyl-4-hydroxyphenyl)propane,-   2,2-bis(3-phenyl-4-hydroxyphenyl)propane,-   2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane,-   2,2-bis(3-chloro-4-hydroxyphenyl)propane,-   2,2-bis(3,5-dichloro-4-hydroxyphenyl)propane,-   2,2-bis(3-bromo-4-hydroxyphenyl)propane,-   2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane,-   2,2-bis(4-hydroxyphenyl)hexafluoropropane,-   1,1-bis(4-hydroxyphenyl)cyclopentane,-   1,1-bis(4-hydroxyphenyl)cyclohexane,-   1,1-bis(3-methyl-4-hydroxyphenyl)cyclohexane,-   1,1-bis(3,5-dimethyl-4-hydroxyphenyl)cyclohexane,-   1,1-bis (3,5-dichloro-4-hydroxyphenyl) cyclohexane,-   1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane,-   1,1-bis(4-hydroxyphenyl)cycloheptane,-   2,2-bis(4-hydroxyphenyl)norbornane,-   2,2-bis(4-hydroxyphenyl)adamantane,-   4,4′-dihydroxydiphenyl ether,-   4,4′-dihydroxy-3,3′-dimethyldiphenyl ether,-   ethylene glycol bis(4-hydroxyphenyl)ether,-   1,3-bis(4-hydroxyphenoxy)benzene,-   1,4-bis(3-hydroxyphenoxy)benzene,-   4,4′-dihydroxydiphenylsulfide,-   3,3′-dimethyl-4,4′-dihydroxydiphenylsulfide,-   3,3′,5,5′-tetramethyl-4,4′-dihydroxydiphenylsulfide,-   4,4′-dihydroxydiphenylsulfoxide,-   3,3′-dimethyl-4,4′-dihydroxydiphenylsulfoxide,-   4,4′-dihydroxydiphenylsulfone,-   3,3′-dimethyl-4,4′-dihydroxydiphenylsulfone,-   3,3′-diphenyl-4,4′-dihydroxydiphenylsulfone,-   3,3′-dichloro-4,4′-dihydroxydiphenylsulfone,-   bis(4-hydroxyphenyl)ketone,-   bis(3-methyl-4-hydroxyphenyl)ketone,-   3,3,3′,3′-tetramethyl-6,6′-dihydroxyspiro(bis)indane,-   3,3′,4,4′-tetrahydro-4,4,4′,4′-tetramethyl-2,2′-spirobi(2H-1-benzopyran)-7,7′-diol,-   trans-2,3-bis(4-hydroxyphenyl)-2-butene,-   9,9-bis(4-hydroxyphenyl)fluorene,-   9,9-bis(4-hydroxyphenyl)xanthene,-   1,6-bis(4-hydroxyphenyl)-1,6-hexanedione,-   α,α,α′,α′-tetramethyl-α,α′-bis(4-hydroxyphenyl)p-xylene,-   α,α,α′,α′-tetramethyl-α,α′-bis(4-hydroxyphenyl)m-xylene,-   2,6-dihydroxybenzo-p-dioxane,-   2,6-dihydroxythianthrene,-   2,7-dihydroxyphenoxathine,-   9,10-dimethyl-2,7-dihydroxyphenazine,-   3,6-dihydroxydibenzofuran,-   3,6-dihydroxydibenzothiophene,-   4,4′-dihydroxybiphenyl,-   1,4-dihydroxynaphthalene,-   2,7-dihydroxypyrene,-   hydroquinone,-   resorcin,-   4-hydroxyphenyl-4-hydroxybenzoate,-   ethylene glycol-bis(4-hydroxybenzoate),-   diethylene glycol-bis(4-hydroxybenzoate),-   triethylene glycol-bis(4-hydroxybenzoate),-   p-phenylene-bis(4-hydroxybenzoate),-   1,6-bis(4-hydroxybenzoyloxy)-1H,1H,6H,6H-perfluorobutane,-   1,4-bis(4-hydroxybenzoyloxy)-1H,1H,4H,4H-perfluorobutane,-   1,3-bis(4-hydroxyphenyl)tetramethyldisiloxane, and phenol-modified    silicone oil.

Further, an aromatic diol having an ester linkage produced by thereaction between 2 moles of a diol and one mole of isophthaloyl chlorideor terephthaloyl chloride is also usable.

Namely, to produce the aromatic polycarbonate resin comprising thestructural unit of formula (2) for use in the photoconductive layer, thediol of formula (11) can be used in combination with the previouslymentioned diol with the charge transporting properties in order toimprove the electrical and mechanical characteristics of the obtainedpolycarbonate resin. Furthermore, the diol of formula (34) may befurther added to the above diols to control the mechanicalcharacteristics of the obtained polycarbonate. In this case, a pluralityof diols of formula (34) may be used in combination. In such a case, thestructural unit of formula (2), and the structural unit with chargetransporting properties are each contained in an amount of 5 wt. % ormore of the total weight of the produced aromatic polycarbonate resin.

When the aforementioned aromatic polycarbonate resin with chargetransporting properties is used as a charge transport medium in thephotoconductive layer of the photoconductor, the charge transport mediummay further comprise a low-molecular charge transport material.

Specific examples of the above-mentioned low-molecular charge transportmaterial are as follows: oxazole derivatives, oxadiazole derivatives(Japanese Laid-Open Patent Applications 52-139065 and 52-139066),imidazole derivatives, triphenylamine derivatives (Japanese Laid-OpenPatent Application 3-285960), benzidine derivatives (Japanese PatentPublication 58-32372), α-phenylstilbene derivatives (Japanese Laid-OpenPatent Application 57-73075), hydrazone derivatives (Japanese Laid-OpenPatent Applications 55-154955, 55-156954, 55-52063, and 56-81850),triphenylmethane derivatives (Japanese Patent Publication 51-10983),anthracene derivatives (Japanese Laid-Open Patent Application 51-94829),styryl derivatives (Japanese Laid-Open Patent Applications 56-29245 and58-198043), carbazole derivatives (Japanese Laid-Open Patent Application58-58552), and pyrene derivatives (Japanese Laid-Open Patent Application2-94812).

According to the present invention, at least one of the previouslymentioned aromatic polycarbonate resins is contained in different ways,for example, in photoconductive layers 2, 2 a, 2 b, 2 c, 2 d, and 2 e,as shown in FIGS. 1 through 6.

In the photoconductor shown in FIG. 1, a photoconductive layer 2 isformed on an electroconductive support 1, which photoconductive layer 2comprises the previously mentioned aromatic polycarbonate resin and asensitizing dye, with the addition thereto of a binder agent (binderresin) when necessary. In this photoconductor, the aromaticpolycarbonate resin works as a photoconductive material, through whichcharge carriers necessary for the light decay of the photoconductor aregenerated and transported. However, the aromatic polycarbonate resinitself scarcely absorbs light in the visible light range and, therefore,it is necessary to add a sensitizing dye which absorbs light in thevisible light range in order to form latent electrostatic images by useof visible light.

Referring to FIG. 2, there is shown an enlarged cross-sectional view ofanother embodiment of an electrophotographic photoconductor according tothe present invention. In this photoconductor, there is formed aphotoconductive layer 2 a on an electroconductive support 1. Thephotoconductive layer 2 a comprises (i) a charge transport medium 4′comprising an aromatic polycarbonate resin having charge transportingproperties according to the present invention, optionally in combinationwith a binder agent, and (ii) a charge generation-material 3 dispersedin the charge transport medium 4′. In this embodiment, the aromaticpolycarbonate resin (or a mixture of the aromatic polycarbonate resinand the binder agent) constitutes the charge transport medium 4′. Thecharge generation material 3, which is, for example, an inorganic ororganic pigment, generates charge carriers. The charge transport medium4′ accepts the charge carriers generated by the charge generationmaterial 3 and transports those charge carriers.

In this electrophotographic photoconductor of FIG. 2, it is basicallynecessary that the light-absorption wavelength regions of the chargegeneration material 3 and the aromatic polycarbonate resin not overlapin the visible light range. This is because, in order that the chargegeneration material 3 produce charge carriers efficiently, it isnecessary that light pass through the charge transport medium 4′ andreach the surface of the charge generation material 3. Since thearomatic polycarbonate resin of the present invention do notsubstantially absorb light with a wavelength of 600 nm or more, it canwork effectively as a charge transport material when used with thecharge generation material 3 which absorbs the light in the visibleregion to the near infrared region and generates charge carriers. Thecharge transport medium 4′ may further comprise the previously mentionedlow-molecular charge transport material.

Referring to FIG. 3, there is shown an enlarged cross-sectional view ofa further embodiment of an electrophotographic photoconductor accordingto the present invention. In the figure, there is formed on anelectroconductive support 1 a two-layered photoconductive layer 2 bcomprising a charge generation layer 5 containing a charge generationmaterial 3, and a charge transport layer 4 comprising an aromaticpolycarbonate resin with the charge-transporting properties according tothe present invention.

In this photoconductor, light which has passed through the chargetransport layer 4 reaches the charge generation layer 5, and chargecarriers are generated within the charge generation layer 5. The chargecarriers which are necessary for the light decay for latentelectrostatic image formation are generated by the charge generationmaterial 3, and accepted and transported by the charge transport layer4. The generation and transportation of the charge carriers areperformed by the same mechanism as that in the photoconductor shown inFIG. 2.

In this case, the charge transport layer 4 comprises the aromaticpolycarbonate resin of the present invention, optionally in combinationwith a binder agent. Furthermore, in order to increase the efficiency ofgenerating the charge carriers, the charge generation layer 5 mayfurther comprise the above-mentioned aromatic polycarbonate resin. Forthe same purpose, the photoconductive layer 2 b including the chargegeneration layer 5 and the charge transport layer 4 may further comprisethe previously mentioned low-molecular charge transport material. Thiscan be applied to the embodiments of FIGS. 4 to 6 to be described later.

In the electrophotographic photoconductor of FIG. 3, a protective layer6 may be provided on the charge transport layer 4 as shown in FIG. 4.The protective layer 6 may comprise the aromatic polycarbonate resin ofthe present invention, optionally in combination with a binder agent.The provision of the protective layer 6 is particularly effective whenthe protective layer 6 is provided on a charge transport layer ofconventional low-molecular charge transport material dispersed type. Theprotective layer 6 may be provided on the photoconductive layer 2 a ofthe photoconductor shown in FIG. 2.

Referring to FIG. 5, there is shown still another embodiment of anelectrophotographic photoconductor according to the present invention.In this figure, the overlaying order of the charge generation layer 5and the charge transport layer 4 comprising the aromatic polycarbonateresin is reversed in view of the electrophotographic photoconductorshown in FIG. 3. The mechanism of generation and transportation of thecharge carriers is substantially the same as that of the photoconductorshown in FIG. 3.

In the above photoconductor of FIG. 5, a protective layer 6 may beformed on the charge generation layer 5 as shown in FIG. 6 in light ofthe mechanical strength of the photoconductor.

When the electrophotographic photoconductor as shown in FIG. 1 isfabricated, at least one aromatic polycarbonate resin with chargetransporting properties is dissolved in a solvent, with the additionthereto of a binder agent when necessary. To the thus prepared solution,a sensitizing dye is added, so that a coating liquid for photoconductivelayer 2 is prepared. The thus prepared photoconductive layer coatingliquid is coated on an electroconductive support 1 and dried, so that aphotoconductive layer 2 is formed on the electroconductive support 1.

It is preferable that the thickness of the photoconductive layer 2 be inthe range of 3 to 50 μm, more preferably in the range of 5 to 40 μm. Itis preferable that the amount of the aromatic polycarbonate resin be inthe range of 30 to 100 wt. % of the total weight of the photoconductivelayer 2. It is preferable that the amount of sensitizing dye for use inthe photoconductive layer 2 be in the range of 0.1 to 5 wt. %, morepreferably in the range of 0.5 to 3 wt. % of the total weight of thephotoconductive layer 2.

Specific examples of the sensitizing dye for use in the presentinvention are triarylmethane dyes such as Brilliant Green, Victoria BlueB, Methyl Violet, Crystal Violet, and Acid Violet 6B; xanthene dyes suchas Rhodamine B, Rhodamine 6G, Rhodamine G Extra, Eosin S, Erythrosin,Rose Bengale, and Fluoresceine; thiazine dyes such as Methylene Blue;and cyanine dyes such as cyanin.

The electrophotographic photoconductor shown in FIG. 2 can be producedby the following method. The finely-divided particles of the chargegeneration material 3 are dispersed in a solution in which at least onearomatic polycarbonate resin of the present invention, or a mixture ofthe aromatic polycarbonate resin and the binder agent is dissolved, sothat a coating liquid for photoconductive layer 2 a is prepared. Thecoating liquid thus prepared is coated on the electroconductive support1 and then dried, whereby the photoconductive layer 2 a is provided onthe electroconductive support 1.

It is preferable that the thickness of the photoconductive layer 2 a bein the range of 3 to 50 μm, more preferably in the range of 5 to 40 μm.It is preferable that the amount of the aromatic polycarbonate resin bein the range of 40 to 100 wt. % of the total weight of thephotoconductive layer 2 a. It is preferable that the amount of thecharge generation material 3 for use in the photoconductive layer 2 a bein the range of 0.1 to 50 wt. %, more preferably in the range of 1 to 20wt. % of the total weight of the photoconductive layer 2 a.

Specific examples of the charge generation material 3 for use in thepresent invention are as follows: inorganic materials such as selenium,selenium—tellurium, cadmium sulfide, cadmium sulfide—selenium, andα-silicon (amorphous silicon); and organic materials, for example, azopigments, such as C.I. Pigment Blue 25 (C.I. 21180), C.I. Pigment Red 41(C.I. 21200), C.I. Acid Red 52 (C.I. 45100), C.I. Basic Red 3 (C.I.45210), an azo pigment having a carbazole skeleton (Japanese Laid-OpenPatent Application 53-95033), an azo pigment having a distyryl benzeneskeleton (Japanese Laid-Open Patent Application 53-133445), an azopigment having a triphenylamine skeleton (Japanese Laid-Open PatentApplication 53-132347), an azo pigment having a dibenzothiopheneskeleton (Japanese Laid-Open Patent Application 54-21728), an azopigment having an oxadiazole skeleton (Japanese Laid-Open PatentApplication 54-12742), an azo pigment having a fluorenone skeleton(Japanese Laid-Open Patent Application 54-22834), an azo pigment havinga bisstilbene skeleton (Japanese Laid-Open Patent Application 54-17733),an azo pigment having a distyryl oxadiazole skeleton (Japanese Laid-OpenPatent Application 54-2129), and an azo pigment having a distyrylcarbazole skeleton (Japanese Laid-Open Patent Application 54-14967);phthalocyanine pigments such as C.I. Pigment Blue 16 (C.I. 74100);indigo pigments such as C.I. Vat Brown 5 (C.I. 73410) and C.I. Vat Dye(C.I. 73030); and perylene pigments such as Algol Scarlet B andIndanthrene Scarlet R (made by Bayer Co., Ltd.). These charge generationmaterials may be used alone or in combination.

When the above-mentioned charge generation material comprises aphthalocyanine pigment, the sensitivity and durability of the obtainedphotoconductor are remarkably improved. In such a case, there can beemployed a phthalocyanine pigment having a phthalocyanine skeleton asindicated by the following formula (35):

In the above formula (35), M (central atom) is a metal atom or hydrogenatom.

To be more specific, as the central atom (M) in the above formula, therecan be employed an atom of H, Li, Be, Na, Mg, Al, Si, K, Ca, Sc, Ti, V,Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag,Cd, In, Sn, Sb, Ba, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Ti, La, Ce, Pr,Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Th, Pa, U, Np, or Am;the combination of atoms forming an oxide, chloride, fluoride,hydroxide, or bromide. The central atom is not limited to theabove-mentioned atoms.

The above-mentioned charge generation material with a phthalocyaninestructure for use in the present invention may have at least the basicstructure as indicated by the above-mentioned formula (35). Therefore,the charge generation material may have a dimer structure or trimerstructure, and further, a polymeric structure. Further, theabove-mentioned basic structure of the above formula (35) may have asubstituent.

Of the phthalocyanine compounds represented by formula (35), anoxotitanium phthalocyanine compound which has the central atom (M) ofTiO in the formula (35), and a metal-free phthalocyanine compound whichhas a hydrogen atom as the central atom (M) are particularly preferredin light of the properties of the obtained photoconductor.

In addition, it is known that each phthalocyanine compound has a varietyof crystal systems. For example, the above-mentioned oxotitaniumphthalocyanine has crystal systems of α-type, β-type, γ-type, m-type,and y-type. In the case of copper phthalocyanine, there are crystalsystems of α-type, β-type, and γ-type. The properties of thephthalocyanine compound vary depending on the crystal system thereofalthough the central metal atom is the same. According to“Electrophotography—the Society Journal—Vol. 29, No. 4 (1990)”, it isreported that the properties of the photoconductor vary depending on thecrystal system of a phthalocyanine contained in the photoconductor. Itis therefore important to select the optimal crystal system of eachphthalocyanine compound to obtain the desired photoconductiveproperties. The oxotitanium phthalocyanine in the y-type crystal systemis particularly advantageous.

A plurality of charge generation materials with phthalocyanine skeletonmay be used in combination in the charge generation layer. Further, suchcharge generation materials with phthalocyanine skeleton may be used incombination with other charge generation materials not havingphthalocyanine skeleton. In this case, inorganic and organicconventional charge generation materials are usable.

Specific examples of the inorganic charge generation materials arecrystalline selenium, amorphous selenium, selenium—tellurium,selenium—tellurium—halogen, selenium—arsenic compound, and α-silicon(amorphous silicon). In particular, when the above-mentioned α-siliconis employed as the charge generation material, it is preferable that thedangling bond be terminated with hydrogen atom or a halogen atom, or bedoped with boron atom or phosphorus atom.

Specific examples of the organic charge generation materials that can beused in combination with the phthalocyanine compound include anazulenium salt pigment, a squaric acid methine pigment, an azo pigmenthaving a carbazole skeleton, an azo pigment having a triphenyl-amineskeleton, an azo pigment having a diphenylamine skeleton, an azo pigmenthaving a dibenzothiophene skeleton, an azo pigment having a fluorenoneskeleton, an azo pigment having an oxadiazole skeleton, an azo pigmenthaving a bisstilbene skeleton, an azo pigment having a distyryloxadiazole skeleton, an azo pigment having a distyryl carbazoleskeleton, a perylene pigment, an anthraquinone pigment, a polycyclicquinone pigment, a quinone imine pigment, a diphenylmethane pigment, atriphenylmethane pigment, a benzoquinone pigment, a naphthoquinonepigment, a cyanine pigment, an azomethine pigment, an indigoid pigment,and a bisbenzimidazole pigment.

The electrophotographic photoconductor shown in FIG. 3 can be producedby the following method. To provide the charge generation layer 5 on theelectroconductive support 1, the charge generation material isvacuum-deposited on the electroconductive support 1. Alternatively, thefinely-divided particles of the charge generation material 3 aredispersed in an appropriate solvent, together with the binder agent whennecessary, so that a coating liquid for charge generation layer 5 isprepared. The thus prepared coating liquid is coated on theelectroconductive support 1 and dried, whereby a charge generation layer5 is formed on the electroconductive support 1. The charge generationlayer 5 may be subjected to surface treatment by buffing and adjustmentof the thickness thereof if required. On the thus formed chargegeneration layer 5, a coating liquid in which at least one aromaticpolycarbonate resin with charge transporting properties, optionally incombination with a binder agent, is dissolved is coated and dried, sothat a charge transport layer 4 is formed on the charge generation layer5. In the charge generation layer 5, the same charge generationmaterials as employed in the above-mentioned photoconductive layer 2 acan be used.

The thickness of the charge generation layer 5 is 5 μm or less,preferably 2 μm or less. It is preferable that the thickness of thecharge transport layer 4 be in the range of 3 to 50 μm, more preferablyin the range of 5 to 40 μm.

When the charge generation layer 5 is provided on the electroconductivesupport 1 by coating the dispersion of finely-divided particles of thecharge generation material 3, it is preferable that the amount offinely-divided particles of the charge generation material 3 for use inthe charge generation layer 5 be in the range of 10 to 100 wt. %, morepreferably in the range of about 50 to 100 wt. % of the total weight ofthe charge generation layer 5. It is preferable that the amount of thearomatic polycarbonate resin of the present invention be in the range of40 to 100 wt. % of the total weight of the charge transport layer 4.

To produce the photoconductor shown in FIG. 4, a coating liquid forprotective layer 6 is prepared by dissolving the previously mentionedaromatic polycarbonate resin, optionally in combination with the binderagent, in a solvent, and the thus obtained coating liquid is coated onthe charge transport layer 4 of the photoconductor shown in FIG. 3, anddried.

It is preferable that the thickness of the protective layer 6 be in therange of 0.15 to 10 μm. It is preferable that the amount of the aromaticpolycarbonate resin for use in the protective layer 6 be in the range of40 to 100 wt. % of the total weight of the protective layer 6.

The electrophotographic photoconductor shown in FIG. 5 can be producedby the following method. The aromatic polycarbonate resin of the presentinvention, optionally in combination with the binder agent, is dissolvedin a solvent to prepare a coating liquid for charge transport layer 4.The thus prepared coating liquid is coated on the electroconductivesupport 1 and dried, whereby a charge transport layer 4 is provided onthe electroconductive support 1. On the thus formed charge transportlayer 4, a coating liquid prepared by dispersing the finely-dividedparticles of the charge generation material 3 in a solvent in which thebinder agent may be dissolved when necessary, is coated, for example, byspray coating, and dried, so that a charge generation layer 5 isprovided on the charge transport layer 4. The amount ratios of thecomponents contained in the charge generation layer 5 and chargetransport layer 4 are the same as those previously mentioned in thedescription of FIG. 3.

When the previously mentioned protective layer 6 is formed on the aboveprepared charge generation layer 5, the electrophotographicphotoconductor shown in FIG. 6 can be fabricated.

To fabricate any of the aforementioned photoconductors of the presentinvention, a metallic plate or foil made of aluminum, a plastic film onwhich a metal such as aluminum is deposited, and a sheet of paper whichhas been treated so as to be electroconductive can be employed as theelectroconductive support 1.

Specific examples of the binder agent used in the preparation of theabove-mentioned coating liquid are condensation resins such aspolyamide, polyurethane, polyester, epoxy resin, polyketone, andpolycarbonate; and vinyl polymers such as polyvinylketone, polystyrene,poly-N-vinylcarbazole, and polyacrylamide. All the resins that haveelectrically insulating properties and adhesion properties can beemployed.

Some plasticizers may be added to the above-mentioned binder agents,when necessary. Examples of the plasticizer for use in the presentinvention are halogenated paraffin, dimethylnaphthalene and dibutylphthalate. Further, a variety of additives such as an antioxidant, alight stabilizer, a thermal stabilizer, and a lubricant may also beadded to the binder agents when necessary.

Furthermore, in the electrophotographic photoconductor according to thepresent invention, an intermediate layer such as an adhesive layer or abarrier layer may be interposed between the electroconductive supportand the photoconductive layer when necessary.

Examples of the material for the intermediate layer are polyamide,nitrocellulose, aluminum oxide, and titanium oxide. It is preferablethat the thickness of the intermediate layer be 1 μm or less.

When copying is performed by use of the photoconductor according to thepresent invention, the surface of the photoconductor is uniformlycharged to a predetermined polarity in the dark. The uniformly chargedphotoconductor is exposed to a light image so that a latentelectrostatic image is formed on the surface of the photoconductor. Thethus formed latent electrostatic image is developed to a visible imageby a developer, and the developed image can be transferred to a sheet ofpaper when necessary.

The photosensitivity and the durability of the electrophotographicphotoconductor according to the present invention are remarkablyimproved.

The electrophotographic image forming apparatus and method, and theprocess cartridge according to the present invention will now beexplained in detail with reference to FIG. 11 to FIG. 13.

FIG. 11 is a schematic view which shows one embodiment of theelectrophotographic image forming method and apparatus employing theelectrophotographic photoconductor according to the present invention.

In FIG. 11, an electrophotographic photoconductor 1 in the form of adrum comprises an electroconductive support, and a photoconductive layerformed thereon comprising the previously mentioned aromaticpolycarbonate resin.

The photoconductor may be in the form of a drum as shown in FIG. 11, asheet, or an endless belt.

As shown in FIG. 11, there are disposed a charger 3, an eraser 4, alight exposing unit 5, a development unit 6, a pre-transfer charger 7,an image transfer charger 10, a separating charger 11, a separator 12, apre-cleaning charger 13, a fur brush 14, a cleaning blade 15, and aquenching lamp 2 around the drum-shaped electrophotographicphotoconductor 1. Reference numeral 8 indicates resist rollers.

The charger 3, the pre-transfer charger 7, the image transfer charger10, the separating charger 11, and the pre-cleaning charger 13 mayemploy the conventional means such as a corotron charger, a scorotroncharger, a solid state charger, and a charging roller. For the imagetransfer means, it is effective to employ both the image transfercharger 10 and the separating charger 11 as illustrated in FIG. 11.

As the light source for the light exposing unit 5 and the quenching lamp2, there can be employed, for example, a fluorescent tube, tungstenlamp, halogen lamp, mercury vapor lamp, sodium light source, lightemitting diode (LED), semiconductor laser (LD), and electroluminescence(EL). Further, a desired wavelength can be obtained by use of variousfilters such as a sharp-cut filter, bandpass filter, a near infrared cutfilter, dichroic filter, interference filter, and color conversionfilter.

The photoconductor may be irradiated with light in the course of theimage transfer step, quenching step, cleaning step, or pre-lightexposure step. In such a case, the above-mentioned light sources areusable.

The toner image formed on the photoconductor 1 using the developmentunit 6 is transferred to a transfer sheet 9. At the step of imagetransfer, all the toner particles deposited on the photoconductor 1 arenot transferred to the transfer sheet 9. Some toner particles remain onthe surface of the photoconductor 1. The remaining toner particles areremoved from the photoconductor 1 using the fur brush 14 and thecleaning blade 15. The cleaning of the photoconductor may be carried outonly by use of a cleaning brush. As the cleaning brush, there can beemployed a conventional fur brush and magnetic fur brush.

When the photoconductor 1 is positively charged, and exposed to lightimages, positive electrostatic latent images are formed on thephotoconductor. In the similar manner as in above, when a negativelycharged photoconductor is exposed to light images, negativeelectrostatic latent images are formed. A negative toner and a positivetoner are respectively used for development of the positiveelectrostatic images and the negative electrostatic images, therebyobtaining positive images. In contrast to this, when the positiveelectrostatic images and the negative electrostatic images arerespectively developed using a positive toner and a negative toner,negative images can be obtained on the surface of the photoconductor 1.Not only such development means, but also the quenching means may employthe conventional manner.

FIG. 12 is a schematic view which shows another embodiment of theelectrophotographic image forming method and apparatus according to thepresent invention.

A photoconductor 21 shown in FIG. 12, which comprises anelectroconductive support and the previously mentioned photoconductivelayer formed thereon, is driven by driving rollers 22 a and 22 b.Charging of the photoconductor 21 is carried out by use of a charger 23,and the charged photoconductor 21 is exposed to light images using animage exposure light 24. Thereafter, latent electrostatic images formedon the photoconductor 21 are developed to toner images using adevelopment unit (not shown), and the toner images are transferred to atransfer sheet with the aid of a transfer charger 25. After the tonerimages are transferred to the transfer sheet, the photoconductor 21 issubjected to pre-cleaning light exposure using a pre-cleaning light 26,and physically cleaned by use of a cleaning brush 27. Finally, quenchingis carried out using a quenching lamp 28. In FIG. 12, theelectroconductive support of the photoconductor 21 has lighttransmission properties, so that it is possible to apply thepre-cleaning light 26 to the electroconductive support side of thephotoconductor 21. As a matter of course, the photoconductive layer sideof the photoconductor 21 may be exposed to the pre-cleaning light.Similarly, the image exposure light 24 and the quenching lamp 28 may bedisposed so that light is directed toward the electroconductive supportside of the photoconductor 21.

The photoconductor 21 is exposed to light using the image exposure light24, the pre-cleaning light 26, and the quenching lamp 28, as illustratedin FIG. 12. In addition to the above, light exposure may be carried outbefore image transfer, and before image exposure.

The above-discussed units, such as the charging unit, light-exposingunit, development unit, image transfer unit, cleaning unit, andquenching unit may be independently fixed in the inside of the copyingmachine, facsimile machine, or printer. Alternatively, at least one ofthose units may be incorporated in a process cartridge together with thephotoconductor. To be more specific, the process cartridge may holdtherein a photoconductor, and at least one of the charging unit,lightexposing unit, development unit, image transfer unit, cleaningunit, or quenching unit, and the process cartridge may by detachably setin the above-mentioned electrophotographic image forming apparatus.

FIG. 13 is a schematic view which shows one example of the processcartridge according to the present invention. In this embodiment of FIG.13, there are disposed a charger 17, a light exposing unit 19, adevelopment roller 20, and a cleaning brush 18 around a photoconductor16.

Other features of this invention will become apparent in the course ofthe following description of exemplary embodiments, which are given forillustration of the invention and are not intended to be limitingthereof.

EXAMPLE 1-1 Synthesis of Aromatic Polycarbonate Resin No. 1

4.30 parts of a diol with charge transporting properties, that is,N-{4-[2,2-bis(4-hydroxyphenyl)vinyl]phenyl}-N,N-bis(4-tolyl)amine, 3.11parts of a diol serving as a comonomer, that is,4,4′-dihydroxy-3,3′-dimethyldiphenylether, and 0.04 parts of a molecularweight modifier, that is, 4-tert-butyl phenol were placed in a reactioncontainer with stirrer.

The above prepared reaction mixture was dissolved with stirring in astream of nitrogen, with the addition thereto of an aqueous solutionprepared by dissolving 4.48 parts of sodium hydroxide and 0.08 parts ofsodium hydrosulfite in 53 parts of water.

Thereafter, the reaction mixture was cooled to 20° C., and vigorouslystirred with the addition thereto of a solution prepared by dissolving3.99 parts of bis(trichloromethyl)carbonate, namely, a trimer ofphosgene, in 44 parts of dichloromethane, thereby forming an emulsion.The polymerization reaction was carried out with the emulsion beingformed.

The reaction mixture was then stirred for 15 minutes at roomtemperature. With the addition of 0.01 parts of triethylamine serving asa catalyst, the reaction mixture was further stirred for 60 minutes atroom temperature. Then, a solution prepared by dissolving 0.18 parts ofphenyl chloroformate serving as a terminator in 5 parts by weight ofdichloromethane was added to the reaction mixture, and the resultantmixture was stirred for 60 minutes at room temperature in order tocontinue the reaction.

Thereafter, by the addition of 200 parts of dichloromethane to thereaction mixture, an organic layer was separated. The resultant organiclayer was successively washed with a 3% aqueous solution of sodiumhydroxide, a 2% aqueous solution of hydrochloric acid, and water.

The thus obtained organic layer was added dropwise to large quantitiesof methanol, whereby a yellow polycarbonate resin was precipitated.Thus, 7.70 parts of a polycarbonate resin No. 1 (in the form of a randomcopolymer) according to the present invention were obtained.

The structural units of the polycarbonate resin No. 1 are shown below,and the composition ratio of each structural unit is put beside thestructural unit, on the supposition that the total number of structuralunits is

The polystyrene-reduced number-average molecular weight (Mn) andweight-average molecular weight (Mw), which were measured by gelpermeation chromatography, were respectively 65,300 and 141,000.

FIG. 7 shows an infrared spectrum of the aromatic polycarbonate resinNo. 1, measured from the cast film on an NaCl plate. The IR spectrumindicates the appearance of the characteristic absorption peak due toC═O stretching vibration of carbonate at 1775 cm⁻¹.

The glass transition temperature (Tg) of the above obtained aromaticpolycarbonate resin No. 1 was 149.5° C. when measured by use of adifferential scanning calorimeter.

The results of the elemental analysis were as follows: % C % H % N Found77.25 4.97 1.38 Calculated 77.21 5.07 1.56

The found values were substantially the same as those obtained bycalculation from the structural formula.

EXAMPLE 1-2 Synthesis of Aromatic Polycarbonate Resin No. 2

The procedure for preparation of the aromatic polycarbonate resin No. 1in Example 1-1 was repeated except thatN-{4-[2,2-bis(4-hydroxyphenyl)vinyl]phenyl}-N,N-bis(4-tolyl)amineemployed as the diol having charge transporting properties in Example1-1 was replaced byN-{4-[2,2-bis(4-hydroxyphenyl)vinyl]biphenyl}-N,N-bis(4-tolyl)amine.Thus, an aromatic polycarbonate resin No. 2 in the form of a randomcopolymer according to the present invention was obtained.

The structural units of the polycarbonate resin No. 2 are shown below.

The polystyrene-reduced number-average molecular weight (Mn) andweight-average molecular weight (Mw), which were measured by gelpermeation chromatography, were respectively 75,800 and 199,000.

FIG. 8 shows an infrared spectrum of the aromatic polycarbonate resinNo. 2, measured from the cast film on an NaCl plate. The IR spectrum ofthe aromatic polycarbonate resin No. 2 indicates the appearance of thecharacteristic absorption peak due to C═O stretching vibration ofcarbonate at 1775 cm⁻¹.

The glass transition temperature (Tg) of the above obtained aromaticpolycarbonate resin No. 2 was 157.3° C. when measured by use of adifferential scanning calorimeter.

The results of the elemental analysis were as follows: % C % H % N Found77.92 4.94 1.37 Calculated 77.98 5.06 1.33

The found values were substantially the same as those obtained bycalculation from the structural formula.

EXAMPLE 1-3 Synthesis of Aromatic Polycarbonate Resin No. 3

2.15 parts of a diol with charge transporting properties, that is,N-{4-[2,2-bis(4-hydroxyphenyl)vinyl]phenyl}-N,N-bis(4-tolyl)amine, 1.57parts of a diol serving as a comonomer, that is,4,4′-dihydroxy-2,2′3,3′-tetramethyldiphenylether, and 0.013 parts of amolecular weight modifier, that is, 4-tert-butyl phenol were placed in areaction container with stirrer.

The above prepared reaction mixture was dissolved with stirring in astream of nitrogen, with the addition thereto of an aqueous solutionprepared by dissolving 3.16 parts of sodium hydroxide and 0.1 parts ofsodium hydrosulfite in 42 parts of water.

Thereafter, the reaction mixture was cooled to 20° C., and vigorouslystirred with the addition thereto of a solution prepared by dissolving1.88 parts of bis(trichloromethyl)carbonate, namely, a trimer ofphosgene, in 28 parts of dichloromethane, thereby forming an emulsion.The polymerization reaction was carried out with the emulsion beingformed.

The reaction mixture was then stirred for 15 minutes at roomtemperature. With the addition of 0.01 parts of triethylamine serving asa catalyst, the reaction mixture was further stirred for 120 minutes atroom temperature to continue the reaction.

Thereafter, by the addition of 200 parts of dichloromethane to thereaction mixture, an organic layer was separated. The resultant organiclayer was successively washed with a 3% aqueous solution of sodiumhydroxide, a 2% aqueous solution of hydrochloric acid, and water.

The thus obtained organic layer was added dropwise to large quantitiesof methanol, whereby a yellow polycarbonate resin was precipitated.Thus, 3.89 parts of a polycarbonate resin No. 3 (in the form of a randomcopolymer) according to the present invention were obtained.

The structural units of the polycarbonate resin No. 3 are shown below,and the composition ratio of each structural unit is put beside thestructural unit, on the supposition that the total number of structuralunits is 1.

The polystyrene-reduced number-average molecular weight (Mn) andweight-average molecular weight (Mw), which were measured by gelpermeation chromatography, were respectively 66,200 and 210,600.

FIG. 9 shows an infrared spectrum of the aromatic polycarbonate resinNo. 3, measured from the cast film on an NaCl plate. The IR spectrumindicates the appearance of the characteristic absorption peak due toC═O stretching vibration of carbonate at 1780 cm⁻¹.

The glass transition temperature (Tg) of the above obtained aromaticpolycarbonate resin No. 3 was 169.6° C. when measured by use of adifferential scanning calorimeter.

The results of the elemental analysis were as follows: % C % H % N Found77.91 5.43 1.36 Calculated 77.87 5.48 1.56

The found values were substantially the same as those obtained bycalculation from the structural formula.

EXAMPLE 1-4 Synthesis of Aromatic Polycarbonate Resin No. 4

2.15 parts of a diol with charge transporting properties, that is,N-{4-[2,2-bis(4-hydroxyphenyl)vinyl]phenyl}-N,N-bis(4-tolyl)amine, 1.57parts of a diol serving as a comonomer, that is,4,4′-dihydroxy-2,2′5,5′-tetramethyldiphenylether, and 0.013 parts of amolecular weight modifier, that is, 4-tert-butyl phenol were placed in areaction container with stirrer.

The above prepared reaction mixture was dissolved with stirring in astream of nitrogen, with the addition thereto of an aqueous solutionprepared by dissolving 3.16 parts of sodium hydroxide and 0.1 parts ofsodium hydrosulfite in 42 parts of water.

Thereafter, the reaction mixture was cooled to 20° C., and vigorouslystirred with the addition thereto of a solution prepared by dissolving1.88 parts of bis(trichloromethyl)carbonate, namely, a trimer ofphosgene, in 28 parts of dichloromethane, thereby forming an emulsion.The polymerization reaction was carried out with the emulsion beingformed.

The reaction mixture was then stirred for 15 minutes at roomtemperature. With the addition of 0.01 parts of triethylamine serving asa catalyst, the reaction mixture was further stirred for 120 minutes atroom temperature to continue the reaction.

Thereafter, by the addition of 200 parts of dichloromethane to thereaction mixture, an organic layer was separated. The resultant organiclayer was successively washed with a 3% aqueous solution of sodiumhydroxide, a 2% aqueous solution of hydrochloric acid, and water.

The thus obtained organic layer was added dropwise to large quantitiesof methanol, whereby a yellow polycarbonate resin was precipitated.Thus, 3.91 parts of a polycarbonate resin No. 4 (in the form of a randomcopolymer) according to the present invention were obtained.

The structural units of the polycarbonate resin No. 4 are shown below,and the composition ratio of each structural unit is put beside thestructural unit, on the supposition that the total number of structuralunits is 1.

The polystyrene-reduced number-average molecular weight (Mn) andweight-average molecular weight (Mw), which were measured by gelpermeation chromatography, were respectively 46,300 and 127,100.

FIG. 10 shows an infrared spectrum of the aromatic polycarbonate resinNo. 4, measured from the cast film on an NaCl plate. The IR spectrumindicates the appearance of the characteristic absorption peak due toC═O stretching vibration of carbonate at 1780 cm⁻¹.

The glass transition temperature (Tg) of the above obtained aromaticpolycarbonate resin No. 4 was 166.9° C. when measured by use of adifferential scanning calorimeter.

The results of the elemental analysis were as follows: % C % H % N Found77.98 5.39 1.46 Calculated 77.87 5.48 1.56

The found values were substantially the same as those obtained bycalculation from the structural formula.

EXAMPLE 2-1 Fabrication of Electrophotographic Photoconductor No. 1

(Formation of Undercoat Layer)

A commercially available polyamide resin (Trademark “CM-8000”, made byToray Industries, Inc.) was dissolved in a mixed solvent of methanol andbutanol, so that a coating liquid for undercoat layer was prepared. Thethus prepared coating liquid was coated on an aluminum plate by a doctorblade, and dried at room temperature, so that an undercoat layer with athickness of 0.3 μm was provided on the aluminum plate.

(Formation of Charge Generation Layer)

A coating liquid for charge generation layer was prepared by pulverizingand dispersing a bisazo compound of the following formula, serving as acharge generation material, in a mixed solvent of cyclohexanone andmethyl ethyl ketone using a ball mill. The thus obtained coating liquidwas coated on the above prepared undercoat layer by a doctor blade, anddried at room temperature. Thus, a charge generation layer with athickness of about 0.5 pm was formed on the undercoat layer.[Bisazo Compound]

(Formation of Charge Transport Layer)

The aromatic polycarbonate resin No. 1 prepared in Example 1-1, servingas a charge transport material, was dissolved in dichloromethane. Thethus obtained coating liquid was coated on the above prepared chargegeneration layer by a doctor blade, and dried at room temperature andthen at 120° C. for 20 minutes, so that a charge transport layer with athickness of 20 μm was provided on the charge generation layer.

Thus, an electrophotographic photoconductor No. 1 according to thepresent invention was fabricated.

EXAMPLES 2-2 TO 2-4

The procedure for fabrication of the electrophotographic photoconductorNo. 1 in Example 2-1 was repeated except that the aromatic polycarbonateresin No. 1 for use in the charge transport layer coating liquid inExample 2-1 was replaced by the aromatic polycarbonate resins No. 2, No.3, and No. 4, respectively in Examples 2-2,2-3, and 2-4.

Thus, electrophotographic photoconductors No. 2, No. 3, and No. 4according to the present invention were fabricated.

Each of the electrophotographic photoconductors No. 1 to No. 4 accordingto the present invention fabricated in Examples 2-1 to 2-4 was chargednegatively in the dark under application of −6 kV of corona charge for20 seconds, using a commercially available electrostatic copying sheettesting apparatus (“Paper Analyzer Model SP-428” made by KawaguchiElectro Works Co., Ltd.). The surface potential (Vm) of eachphotoconductor was measured.

Then, each electrophotographic photoconductor was allowed to stand inthe dark for 20 seconds without applying any charge thereto, and thesurface potential (Vo) of the photoconductor was measured.

Each photoconductor was then illuminated by a tungsten lamp in such amanner that the illuminance on the illuminated surface of thephotoconductor was 4.5 lux, and the exposure E_(1/2) (lux·sec) requiredto reduce the initial surface potential Vo (V) to ½ the initial surfacepotential Vo (V) was measured.

The results are shown in TABLE 1. TABLE 1 Example Polycarbonate Vm VoE_(1/2) No. Resin No. (V) (V) (lux · sec) 2-1 No. 1 −1316 −1194 1.23 2-2No. 2 −1447 −1320 1.38 2-3 No. 3 −1519 −1408 1.53 2-4 No. 4 −1566 −14611.61

COMPARATIVE EXAMPLE 1

The procedure for fabrication of the electrophotographic photoconductorNo. 1 in Example 2-1 was repeated except that the aromatic polycarbonateresin No. 1 for use in the charge transport layer coating liquid inExample 2-1 was replaced by an aromatic polycarbonate resin with aweight-average molecular weight of 126,000 and a number-averagemolecular weight of 55,700, represented by the following formula.

Thus, a comparative electrophotographic photoconductor No. 1 wasfabricated.

COMPARATIVE EXAMPLE 2

The procedure for fabrication of the electrophotographic photoconductorNo. 1 in Example 2-1 was repeated except that the aromatic polycarbonateresin No. 1 for use in the charge transport layer coating liquid inExample 2-1 was replaced by an aromatic polycarbonate resin with aweight-average molecular weight of 207,900 and a number-averagemolecular weight of 83,600, represented by the following formula.

Thus, a comparative electrophotographic photoconductor No. 2 wasfabricated.

The electrophotographic photoconductors Nos. 1 to 4 according to thepresent invention fabricated in Examples 2-1 to 2-4 and the comparativeelectrophotographic photoconductors Nos. 1 and 2 fabricated inComparative Examples 1 and 2 were subjected to an abrasion test inaccordance with JIS K 7204(1995), using a commercially available Taberabrader with truck wheels (CS-5), made by Toyo Seiki Seisaku-sho, Ltd.

The abrasion amount of each photoconductor was measured under theapplication of a load of 1 kg after 3000 rotations.

The results are shown in TABLE 2. TABLE 2 Abrasion Amount Example No.(mg) Example 2-1 0.61 Example 2-2 0.54 Example 2-3 1.13 Example 2-4 0.94Comparative 2.02 Example 1 Comparative 4.30 Example 2

As is apparent from the results shown in TABLE 2, the abrasionresistance of the photoconductor according to the present invention isconsidered to be superior to that of the conventional photoconductoremploying the high-molecular charge transport materials. Consequently,the photoconductors of the present invention show high durability interms of the abrasion resistance.

EXAMPLE 2-5

Fabrication of Electrophotographic Photoconductor No. 5

(Formation of Undercoat Layer)

A coating liquid with the following formulation was coated on the outersurface of an aluminum drum with a diameter of 30 mm, and dried. Thus,an undercoat layer with a thickness of 3.5 μm was provided on thealuminum drum. Parts by Weight Alkyd resin (Trademark 6 “Beckosol1307-60-EL”, made by Dainippon Ink & Chemicals, Incorporated) Melamineresin (Trademark 4 “Super Beckamine G-821-60”, made by Dainippon Ink &Chemicals, Incorporated) Titanium oxide 40 Methyl ethyl ketone 50[Formation of Charge Generation Layer]

A coating liquid with the following formulation was coated on the aboveprepared undercoat layer, and dried. Thus, a charge generation layerwith a thickness of 0.2 μm was provided on the undercoat layer. Parts byWeight Oxotitanium phthalocyanine 3 pigment (charge generation material)Poly(vinyl butyral) (Trademark 2 “XYHL”, made by Union Carbide JapanK.K.) Tetrahydrofuran 95[Formation of Charge Transport Layer]

A coating liquid with the following formulation was coated on the aboveprepared charge generation layer, and dried. Thus, a charge transportlayer with a thickness of 30±1 μm was provided on the charge generationlayer. Parts by Weight Polycarbonate resin No. 1 10 (prepared in Example1-1) Methylene chloride 90

Thus, an electrophotographic photoconductor No. 5 according to thepresent invention was fabricated.

EXAMPLES 2-6 TO 2-8

The procedure for fabrication of the electrophotographic photoconductorNo. 5 in Example 2-5 was repeated except that the aromatic polycarbonateresin No. 1 for use in the charge transport layer coating liquid inExample 2-5 was replaced by the aromatic polycarbonate resins No. 2, No.3, and No. 4, respectively in Examples 2-6,2-7, and 2-8.

Thus, electrophotographic photoconductors No. 6, No. 7, and No. 8according to the present invention were fabricated.

COMPARATIVE EXAMPLE 3

The procedure for fabrication of the electrophotographic photoconductorNo. 5 in Example 2-5 was repeated except that the formulation for thecharge transport layer coating liquid in Example 2-5 was changed to thefollowing formulation: Parts by Weight Bisphenol Z type polycarbonate 10(Trademark “PCX-5”, made by Teijin Chemicals Ltd.) Low-molecular charge7 transport material with the following formula:

Methylene chloride 150

Thus, a comparative electrophotographic photoconductor No. 3 wasfabricated.

Then, each of the electrophotographic photoconductors Nos. 5 to 8according to the present invention and the comparativeelectrophotographic photoconductor No. 3 was set in a commerciallyavailable copying machine “imagio MF200” (Trademark), made by RicohCompany, Ltd., which was partially modified to have such a structure asshown in FIG. 11. A copying test was continuously carried out for 40hours. The difference between the thickness of the photoconductive layerbefore the copying test and the thickness after the copying test wasmeasured as the abrasion wear (μm). The results are shown in TABLE 3.TABLE 3 Abrasion Wear Example No. (μm) Example 2-5 2.11 Example 2-6 1.89Example 2-7 1.42 Example 2-8 1.58 Comparative 4.00 Example 3

The results of TABLE 3 show that the abrasion resistance of theelectrophotographic photoconductor according to the present invention isexcellent.

Further, each of the electrophotographic photoconductors according tothe present invention was set in a commercially availableelectrophotographic copying machine, and the photoconductor was chargedand exposed to light images via original images to form latentelectrostatic images thereon. Then, the latent electrostatic imagesformed on the photoconductor were developed into visible toner images bya dry developer, and the visible toner images were transferred to asheet of plain paper and fixed thereon. As a result, clear toner imageswere obtained on the paper. When a wet developer was employed for theimage formation, clear images were formed on the paper similarly.

EXAMPLE 2-9

[Fabrication of Electrophotographic Photoconductor No. 9]

(Formation of Undercoat Layer)

A coating liquid with the following formulation was coated on thesurface of an electromolded nickel belt, and dried. Thus, an undercoatlayer with a thickness of about 6 μm was provided on the nickel belt.Parts by Weight Titanium oxide (TA-300) 5 Copolymer polyamide resin 4(Trademark “CM-8000”, made by Toray Industries, Inc.) Methanol 50Isopropanol 20[Formation of Charge Generation Layer]

A coating liquid with the following formulation was coated on the aboveprepared undercoat layer, and dried. Thus, a charge generation layerwith a thickness of about 0.3 μm was provided on the undercoat layer.Parts by Weight y-type oxotitanium phthalocyanine 4 pigment particles(charge generation material) Poly(vinyl butyral) 2 Cyclohexanone 50Tetrahydrofuran 100[Formation of charge transport layer]

A coating liquid with the following formulation was coated on the aboveprepared charge generation layer, and dried. Thus, a charge transportlayer with a thickness of 24 μm was provided on the charge generationlayer. Parts by Weight Polycarbonate resin No. 1 10 (prepared in Example1-1) Tetrahydrofuran 60

Thus, an electrophotographic photoconductor No. 9 according to thepresent invention was fabricated.

EXAMPLES 2-10 TO 2-12

The procedure for fabrication of the electrophotographic photoconductorNo. 9 in Example 2-9 was repeated except that the aromatic polycarbonateresin No. 1 for use in the charge transport layer coating liquid inExample 2-9 was replaced by the aromatic polycarbonate resins No. 2, No.3, and No. 4, respectively in Examples 2-10, 2-11, and 2-12.

Thus, electrophotographic photoconductors No. 10, No. 11, and No. 12according to the present invention were fabricated.

Each of the electrophotographic photoconductors No. 9 to No. 12according to the present invention was incorporated in the sameelectrophotographic image forming apparatus as shown in FIG. 12 exceptthat the pre-cleaning light 26 was omitted. Using a semiconductor laserbeam of 780 nm as the image exposure light 24, light images were writtenthrough a polygon mirror. A probe of a potentiometer was put into thephotoconductor to measure the surface potential of the photoconductorimmediately before development was conducted. The surface potentials ofa non-light exposed portion and a light-exposed portion were measured atthe initial stage and after making of 10,000 copies. The results areshown in TABLE 4. TABLE 4 After Making of 10,000 Copies At Initial StageSurface Surface Surface potential Surface potetial of potential of non-potential non-light of light- light of light- Exam- Polycarbonateexposed exposed exposed exposed ple Resin portion portion portionportion No. No. (V) (V) (V) (V) 2-9  1 −855 −35 −845 −51 2-10 2 −845 −45−826 −49 2-11 3 −829 −55 −808 −60 2-12 4 −835 −42 −822 −56

EXAMPLE 2-13

An aluminum cylinder serving as an electroconductive support wassurface-treated by anodizing, followed by sealing.

On the outer surface of the thus prepared aluminum cylinder, a chargegeneration layer and a charge transport layer were successively overlaidin the same manner as in Example 2-9. Thus, an electrophotographicphotoconductor No. 13 according to the present invention was fabricated.

EXAMPLES 2-14 TO 2-16

The procedure for fabrication of the electrophotographic photoconductorNo. 13 in Example 2-13 was repeated except that the aromaticpolycarbonate resin No. 1 for use in the charge transport layer coatingliquid in Example 2-13 was replaced by the aromatic polycarbonate resinsNo. 2, No. 3, and No. 4, respectively in Examples 2-14, 2-15, and 2-16.

Thus, electrophotographic photoconductors No. 14, No. 15, and No. 16according to the present invention were fabricated.

Each of the electrophotographic photoconductors No. 13 to No. 16according to the present invention was incorporated in theelectrophotographic process cartridge as shown in FIG. 13, and theprocess cartridge was set in the electrophotographic image formingapparatus. Using a semiconductor laser beam of 780 nm as the lightsource for image exposure, light images were written through a polygonmirror. A probe of a potentiometer was put into the photoconductor tomeasure the surface potential of the photoconductor immediately beforedevelopment was conducted. The surface potentials of a non-light exposedportion and a light-exposed portion were measured at the initial stageand after making of 5,000 copies. The results are shown in TABLE 5.TABLE 5 After Making of 5,000 Copies At Initial Stage Surface SurfaceSurface potential Surface potetial of potential of non- potentialnon-light of light- light of light- Exam- Polycarbonate exposed exposedexposed exposed ple Resin portion portion portion portion No. No. (V)(V) (V) (V) 2-13 1 −834 −55 −837 −61 2-14 2 −842 −62 −815 −68 2-15 3−855 −58 −829 −64 2-16 4 −848 −64 −838 −69

As can be seen from the results shown in TABLE 4 and TABLE 5, thesurface potential of the electrophotographic photoconductor of thepresent invention can be maintained stable after repeated use.

As previously explained, the polycarbonate resins of the presentinvention, for example, comprising the structural unit of formula (2)can provide polymeric materials with minimum mechanical abrasion. Inaddition, these polycarbonate resins can effectively function asphotoconductive materials in the electrophotographic photoconductor.Such polycarbonate resins are optically or chemically sensitized with asensitizer such as a dye or a Lewis acid. These resin compounds arepreferably employed as charge transport materials in a photoconductivelayer of the electrophotographic photoconductor, in particular, of afunction-separating electrophotographic photoconductor comprising acharge generation layer and a charge transport layer because thesepolycarbonate resins are provided with high charge transportingproperties and high mechanical strength.

The polycarbonate resin for use in the photoconductive layer of theelectrophotographic photoconductor according to the present inventioncomprises at least the structural unit of formula (2), and a structuralunit having charge transporting properties. Furthermore, a polycarbonateresin in the form of a random copolymer comprising the structural unitof formula (2) and the structural unit of formula (1′) or (1), and apolycarbonate resin in the form of an alternating copolymer comprisingthe repeat unit of formula (3′) or (3) are employed in theelectrophotographic photoconductors of the present invention.

In any case, the polycarbonate resin for use in the present inventioncomprises at least the structural unit of formula (2), so that apolymeric material with minimum mechanical abrasion can be provided.When the above-mentioned polycarbonate resin is employed in thephotoconductive layer of the electrophotographic photoconductor, theabrasion resistance of the photoconductor is remarkably improved.Further, the polycarbonate resin comprising the structural unit offormula (2) and the structural unit having charge transportingproperties has excellent mechanical strength and sufficient chargetransporting properties, so that the obtained photoconductor can exhibithigh sensitivity and high durability.

Japanese Patent Applications Nos. 11-191652 and 11-191667 filed on Jul.6, 1999 are hereby incorporated by reference.

1. An aromatic polycarbonate resin comprising a structural unit offormula (1) and a structural unit of formula (2), with the relationshipbetween the composition ratios being 0<k/(k+j)<1 when the compositionratio of said structural unit of formula (1) is k and that of saidstructural unit of formula (2) is j:

wherein R¹ and R², which may be the same or different, are each an acylgroup, an alkyl group having 1 to 6 carbon atoms, which may have asubstituent, or an aryl group which may have a substituent; and Ar¹,Ar², and Ar³ are each a substituted or unsubstituted arylene group;

wherein a and b are each independently an integer of 1 to 4; and R³ andR⁴ are each independently a halogen atom, an alkyl group having 1 to 6carbon atoms, which may have a substituent, an alkoxyl group having 1 to6 carbon atoms, which may have a substituent, or an aryl group which mayhave a substituent, and R³ and R⁴ may each be the same or different whena and b are each an integer of 2, 3 or
 4. 2. An aromatic polycarbonateresin comprising a repeat unit of formula (3):

wherein R¹ and R², which may be the same or different, are each an acylgroup, an alkyl group having 1 to 6 carbon atoms, which may have asubstituent, or an aryl group which may have a substituent; Ar¹, Ar²,and Ar³ are each a substituted or unsubstituted arylene group; a and bare each independently an integer of 1 to 4; R³ and R⁴ are eachindependently a halogen atom, an alkyl group having 1 to 6 carbon atoms,which may have a substituent, an alkoxyl group having 1 to 6 carbonatoms, which may have a substituent, or an aryl group which may have asubstituent, and R³ and R⁴ may each be the same or different when a andb are each an integer of 2, 3 or 4; and n is an integer of 2 to 5,000,which represents a degree of polymerization.
 3. An aromaticpolycarbonate resin comprising a structural unit of formula (4) and astructural unit of formula (2), with the relationship between thecomposition ratios being 0<k/(k+j)<1 when the composition ratio of saidstructural unit of formula (4) is k and that of said structural unit offormula (2) is j:

wherein c and d are each independently an integer of 0 to 5; R⁵ and R⁶are each independently a halogen atom, an alkyl group having 1 to 6carbon atoms, which may have a substituent, an alkoxyl group having 1 to6 carbon atoms, which may have a substituent, or an aryl group which mayhave a substituent, and R⁵ and R⁶ may each be the same or different whenc and d are each an integer of 2, 3, 4 or 5; and Ar³ is a substituted orunsubstituted arylene group;

wherein a and b are each independently an integer of 1 to 4; and R³ andR⁴ are each independently a halogen atom, an alkyl group having 1 to 6carbon atoms, which may have a substituent, an alkoxyl group having 1 to6 carbon atoms, which may have a substituent, or an aryl group which mayhave a substituent, and R³ and R⁴ may each be the same or different whena and b are each an integer of 2, 3 or
 4. 4. An aromatic polycarbonateresin comprising a repeat unit of formula (5):

wherein c and d are each independently an integer of 0 to 5; R⁵ and R⁶are each independently a halogen atom, an alkyl group having 1 to 6carbon atoms, which may have a substituent, an alkoxyl group having 1 to6 carbon atoms, which may have a substituent, or an aryl group which mayhave a substituent, and R⁵ and R⁶ may each be the same or different whenc and d are each an integer of 2, 3, 4 or 5; Ar³ is a substituted orunsubstituted arylene group; a and b are each independently an integerof 1 to 4; R³ and R⁴ are each independently a halogen atom, an alkylgroup having 1 to 6 carbon atoms, which may have a substituent, analkoxyl group having 1 to 6 carbon atoms, which may have a substituent,or an aryl group which may have a substituent, and R³ and R⁴ may each bethe same or different when a and b are each an integer of 2, 3 or 4; andn is an integer of 2 to 5,000, which represents a degree ofpolymerization.
 5. An aromatic polycarbonate resin comprising astructural unit of formula (1) and a structural unit of formula (6),with the relationship between the composition ratios being 0<k/(k+j)<1when the composition ratio of said structural unit of formula (1) is kand that of said structural unit of formula (6) is j:

wherein R¹ and R², which may be the same or different, are each an acylgroup, an alkyl group having 1 to 6 carbon atoms, which may have asubstituent, or an aryl group which may have a substituent; and Ar¹,Ar², and Ar³ are each a substituted or unsubstituted arylene group;

wherein R³ and R⁴ are each independently a halogen atom, an alkyl grouphaving 1 to 6 carbon atoms, which may have a substituent, an alkoxylgroup having 1 to 6 carbon atoms, which may have a substituent, or anaryl group which may have a substituent; and R⁷ and R⁸ are eachindependently a hydrogen atom, a halogen atom, an alkyl group having 1to 6 carbon atoms, which may have a substituent, an alkoxyl group having1 to 6 carbon atoms, which may have a substituent, or an aryl groupwhich may have a substituent.
 6. An aromatic polycarbonate resincomprising a repeat unit of formula (7):

wherein R¹ and R², which may be the same or different, are each an acylgroup, an alkyl group having 1 to 6 carbon atoms, which may have asubstituent, or an aryl group which may have a substituent; Ar¹, Ar²,and Ar³ are each a substituted or unsubstituted arylene group; R³ and R⁴are each independently a halogen atom, an alkyl group having 1 to 6carbon atoms, which may have a substituent, an alkoxyl group having 1 to6 carbon atoms, which may have a substituent, or an aryl group which mayhave a substituent; R⁷ and R⁸ are each independently a hydrogen atom, ahalogen atom, an alkyl group having 1 to 6 carbon atoms, which may havea substituent, an alkoxyl group having 1 to 6 carbon atoms, which mayhave a substituent, or an aryl group which may have a substituent; and nis an integer of 2 to 5,000, which represents a degree ofpolymerization.
 7. An aromatic polycarbonate resin comprising astructural unit of formula (4) and a structural unit of formula (6),with the relationship between the composition ratios being 0<k/(k+j)<1when the composition ratio of said structural unit of formula (4) is kand that of said structural unit of formula (6) is j:

wherein c and d are each independently an integer of 0 to 5; R⁵ and R⁶are each independently a halogen atom, an alkyl group having 1 to 6carbon atoms, which may have a substituent, an alkoxyl group having 1 to6 carbon atoms, which may have a substituent, or an aryl group which mayhave a substituent, and R⁵ and R⁶ may each be the same or different whenc and d are each an integer of 2, 3, 4 or 5; and Ar³ is a substituted orunsubstituted arylene group;

wherein R³ and R⁴ are each independently a halogen atom, an alkyl grouphaving 1 to 6 carbon atoms, which may have a substituent, an alkoxylgroup having 1 to 6 carbon atoms, which may have a substituent, or anaryl group which may have a substituent; and R⁷ and R⁸ are eachindependently a hydrogen atom, a halogen atom, an alkyl group having 1to 6 carbon atoms, which may have a substituent, an alkoxyl group having1 to 6 carbon atoms, which may have a substituent, or an aryl groupwhich may have a substituent.
 8. An aromatic polycarbonate resincomprising a repeat unit of formula (8):

wherein c and d are each independently an integer of 0 to 5; R⁵ and R⁶are each independently a halogen atom, an alkyl group having 1 to 6carbon atoms, which may have a substituent, an alkoxyl group having 1 to6 carbon atoms, which may have a substituent, or an aryl group which mayhave a substituent, and R⁵ and R⁶ may each be the same or different whenc and d are each an integer of 2, 3, 4 or 5; Ar³ is a substituted orunsubstituted arylene group; R³ and R⁴ are each independently a halogenatom, an alkyl group having 1 to 6 carbon atoms, which may have asubstituent, an alkoxyl group having 1 to 6 carbon atoms, which may havea substituent, or an aryl group which may have a substituent; R⁷ and R⁸are each independently a hydrogen atom, a halogen atom, an alkyl grouphaving. 1 to 6 carbon atoms, which may have a substituent, an alkoxylgroup having 1 to 6 carbon atoms, which may have a substituent, or anaryl group which may have a substituent; and n is an integer of 2 to5,000, which represents a degree of polymerization.
 9. An aromaticpolycarbonate resin comprising a structural unit of formula (1), and astructural unit of formula (23), with the relationship between thecomposition ratios being 0<k/(k+j)<1 when the composition ratio of saidstructural unit of formula (1) is k and that of said structural unit offormula (23) is j:

wherein R¹ and R², which may be the same or different, are each an acylgroup, an alkyl group having 1 to 6 carbon atoms, which may have asubstituent, or an aryl group which may have a substituent; and Ar¹,Ar², and Ar³ are each a substituted or unsubstituted arylene group;

wherein R³ and R⁴ are each independently a halogen atom, an alkyl grouphaving 1 to 6 carbon atoms, which may have a substituent, an alkoxylgroup having 1 to 6 carbon atoms, which may have a substituent, or anaryl group which may have a substituent; and R⁹ and R¹⁰ are eachindependently a halogen atom, an alkyl group having 1 to 6 carbon atoms,which may have a substituent, an alkoxyl group having 1 to 6 carbonatoms, which may have a substituent, or an aryl group which may have asubstituent.
 10. An aromatic polycarbonate resin comprising a repeatunit of formula (25):

wherein R¹ and R², which may be the same or different, are each an acylgroup, an alkyl group having 1 to 6 carbon atoms, which may have asubstituent, or an aryl group which may have a substituent; Ar¹, Ar²,and Ar³ are each a substituted or unsubstituted arylene group; R³ and R⁴are each independently a halogen atom, an alkyl group having 1 to 6carbon atoms, which may have a substituent, an alkoxyl group having 1 to6 carbon atoms, which may have a substituent, or an aryl group which mayhave a substituent; R⁹ and R¹⁰ are each independently a halogen atom, analkyl group having 1 to 6 carbon atoms, which may have a substituent, analkoxyl group having 1 to 6 carbon atoms, which may have a substituent,or an aryl group which may have a substituent; and n is an integer of 2to 5,000, which represents a degree of polymerization.
 11. An aromaticpolycarbonate resin comprising a structural unit of formula (1), and astructural unit of formula (24), with the relationship between thecomposition ratios being 0<k/(k+j)<1 when the composition ratio of saidstructural unit of formula (1) is k and that of said structural unit offormula (24) is j:

wherein R¹ and R², which may be the same or different, are each an acylgroup, an alkyl group having 1 to 6 carbon atoms, which may have asubstituent, or an aryl group which may have a substituent; and Ar¹,Ar², and Ar³ are each a substituted or unsubstituted arylene group;

wherein R³ and R⁴ are each independently a halogen atom, an alkyl grouphaving 1 to 6 carbon atoms, which may have a substituent, an alkoxylgroup having 1 to 6 carbon atoms, which may have a substituent, or anaryl group which may have a substituent; and R⁹ and R¹⁰ are eachindependently a halogen atom, an alkyl group having 1 to 6 carbon atoms,which may have a substituent, an alkoxyl group having 1 to 6 carbonatoms, which may have a substituent, or an aryl group which may have asubstituent.
 12. An aromatic polycarbonate resin comprising a repeatunit of formula (26):

wherein R¹ and R², which may be the same or different, are each an acylgroup, an alkyl group having 1 to 6 carbon atoms, which may have asubstituent, or an aryl group which may have a substituent; Ar¹, Ar²,and Ar³ are each a substituted or unsubstituted arylene group; R³ and R⁴are each independently a halogen atom, an alkyl group having 1 to 6carbon atoms, which may have a substituent, an alkoxyl group having 1 to6 carbon atoms, which may have a substituent, or an aryl group which mayhave a substituent; R⁹ and R¹⁰ are each independently a halogen atom, analkyl group having 1 to 6 carbon atoms, which may have a substituent, analkoxyl group having 1 to 6 carbon atoms, which may have a substituent,or an aryl group which may have a substituent; and n is an integer of 2to 5,000, which represents a degree of polymerization.
 13. An aromaticpolycarbonate resin comprising a structural unit of formula (4), and astructural unit of formula (23), with the relationship between thecomposition ratios being 0<k/(k+j)<1 when the composition ratio of saidstructural unit of formula (4) is k and that of said structural unit offormula (23) is j:

wherein c and d are each independently an integer of 0 to 5; R⁵ and R⁶are each independently a halogen atom, an alkyl group having 1 to 6carbon atoms, which may have a substituent, an alkoxyl group having 1 to6 carbon atoms, which may have a substituent, or an aryl group which mayhave a substituent, and R⁵ and R⁶ may each be the same or different whenc and d are each an integer of 2, 3, 4 or 5; and Ar³ is a substituted orunsubstituted arylene group;

wherein R³ and R⁴ are each independently a halogen atom, an alkyl grouphaving 1 to 6 carbon atoms, which may have a substituent, an alkoxylgroup having 1 to 6 carbon atoms, which may have a substituent, or anaryl group which may have a substituent; and R⁹ and R¹⁰ are eachindependently a halogen atom, an alkyl group having 1 to 6 carbon atoms,which may have a substituent, an alkoxyl group having 1 to 6 carbonatoms, which may have a substituent, or an aryl group which may have asubstituent.
 14. An aromatic polycarbonate resin comprising a repeatunit of formula (27):

wherein c and d are each independently an integer of 0 to 5; R⁵ and R⁶are each independently a halogen atom, an alkyl group having 1 to 6carbon atoms, which may have a substituent an alkoxyl group having 1 to6 carbon atoms which may have a substituent, or an aryl group which mayhave a substituent, and R⁵ and R⁶ may each be the same or different whenc and d are each an integer of 2, 3, 4 or 5; Ar³ is a substituted orunsubstituted arylene group; R³ and R⁴ are each independently a halogenatom, an alkyl group having 1 to 6 carbon atoms, which may have asubstituent, an alkoxyl group having 1 to 6 carbon atoms, which may havea substituent, or an aryl group which may have a substituent; R⁹ and R¹⁰are each independently a halogen atom, an alkyl group having 1 to 6carbon atoms, which may have a substituent, an alkoxyl group having 1 to6 carbon atoms, which may have a substituent, or an aryl group which mayhave a substituent; and n is an integer of 2 to 5,000, which representsa degree of polymerization.
 15. An aromatic polycarbonate resincomprising a structural unit of formula (4), and a structural unit offormula (24), with the relationship between the composition ratios being0<k/(k+j)<1 when the composition ratio of said structural unit offormula (4) is k and that of said structural unit of formula (24) is j:

wherein c and d are each independently an integer of 0 to 5; R⁵ and R⁶are each independently a halogen atom, an alkyl group having 1 to 6carbon atoms, which may have a substituent, an alkoxyl group having 1 to6 carbon atoms, which may have a substituent, or an aryl group which mayhave a substituent, and R⁵ and R⁶ may each be the same or different whenc and d are each an integer of 2, 3, 4 or 5; and Ar³ is a substituted orunsubstituted arylene group;

wherein R³ and R⁴ are each independently a halogen atom, an alkyl grouphaving 1 to 6 carbon atoms, which may have a substituent, an alkoxylgroup having 1 to 6 carbon atoms, which may have a substituent, or anaryl group which may have a substituent; and R⁹ and R¹⁰ are eachindependently a halogen atom, an alkyl group having 1 to 6 carbon atoms,which may have a substituent, an alkoxyl group having 1 to 6 carbonatoms, which may have a substituent, or an aryl group which may have asubstituent.
 16. An aromatic polycarbonate resin comprising a repeatunit of formula (28):

wherein c and d are each independently an integer of 0 to 5; R⁵ and R⁶are each independently a halogen atom, an alkyl group having 1 to 6carbon atoms, which may have a substituent, an alkoxyl group having 1 to6 carbon atoms, which may have a substituent, or an aryl group which mayhave a substituent, and R⁵ and R⁶ may each be the same or different whenc and d are each an integer of 2, 3, 4 or 5; Ar³ is a substituted orunsubstituted arylene group; R³ and R⁴ are each independently a halogenatom, an alkyl group having 1 to 6 carbon atoms, which may have asubstituent, an alkoxyl group having 1 to 6 carbon atoms, which may havea substituent, or an aryl group which may have a substituent; R⁹ and R¹⁰are each independently a halogen atom, an alkyl group having 1 to 6carbon atoms, which may have a substituent, an alkoxyl group having 1 to6 carbon atoms, which may have a substituent, or an aryl group which mayhave a substituent; and n is an integer of 2 to 5,000, which representsa degree of polymerization.
 17. An electrophotographic photoconductorcomprising an electroconductive support, and a photoconductive layerformed thereon comprising as an effective component an aromaticpolycarbonate resin which comprises a structural unit of formula (2) anda structural unit with charge transporting properties, each of saidstructural units being contained in an amount of 5 wt. % or more of thetotal weight of said polycarbonate resin:

wherein a and b are each independently an integer of 1 to 4; and R³ andR⁴ are each independently a halogen atom, an alkyl group having 1 to 6carbon atoms, which may have a substituent, an alkoxyl group having 1 to6 carbon atoms, which may have a substituent, or an aryl group which mayhave a substituent, and R³ and R⁴ may each be the same or different whena and b are each an integer of 2, 3 or 4; wherein said structural unitwith charge transporting properties is contained in an amount of 10 to90 wt. % of the total weight of said polycarbonate resin. 18.(Canceled):
 19. An electrophotographic photoconductor comprising anelectroconductive support, and a photoconductive layer formed thereoncomprising as an effective component an aromatic polycarbonate resinwhich comprises a structural unit of formula (2) and a structural unitwith charge transporting properties, each of said structural units beingcontained in an amount of 5 wt. % or more of the total weight of saidpolycarbonate resin:

wherein a and b are each independently an integer of 1 to 4; and R³ andR⁴ are each independently a halogen atom, an alkyl group having 1 to 6carbon atoms, which may have a substituent, an alkoxyl group having 1 to6 carbon atoms, which may have a substituent, or an aryl group which mayhave a substituent, and R³ and R⁴ may each be the same or different whena and b are each an integer of 2, 3 or 4; wherein said structural unitwith charge transporting properties is represented by formula (1′):

wherein R¹¹ is a hydrogen atom, an alkyl group which may have asubstituent, or an aryl group which may have a substituent; Ar¹ and Ar²are each an arylene group which may have a substituent; and R¹² is anaryl group which may have a substituent.
 20. The electrophotographicphotoconductor as claimed in claim 19, wherein said structural unit (1′)with charge transporting properties is contained in an amount of 10 to90 wt. % of the total weight of said polycarbonate resin.
 21. Anelectrophotographic photoconductor comprising an electroconductivesupport, and a photoconductive layer formed thereon comprising as aneffective component an aromatic polycarbonate resin which comprises astructural unit of formula (2) and a structural unit with chargetransporting properties, each of said structural units being containedin an amount of 5 wt. % or more of the total weight of saidpolycarbonate resin:

wherein a and b are each independently an integer of 1 to 4; and R³ andR⁴ are each independently a halogen atom, an alkyl group having 1 to 6carbon atoms, which may have a substituent, an alkoxyl group having 1 to6 carbon atoms, which may have a substituent, or an aryl group which mayhave a substituent, and R³ and R⁴ may each be the same or different whena and b are each an integer of 2, 3 or 4: wherein said aromaticpolycarbonate resin comprises a repeat unit of formula (3′):

wherein R¹¹ is a hydrogen atom, an alkyl group which may have asubstituent, or an aryl group which may have a substituent; Ar¹ and Ar²are each an arylene group which may have a substituent; R¹² is an arylgroup which may have a substituent; a and b are each independently aninteger of 1 to 4; R³ and R⁴ are each independently a halogen atom, analkyl group having 1 to 6 carbon atoms, which may have a substituent, analkoxyl group having 1 to 6 carbon atoms, which may have a substituent,or an aryl group which may have a substituent, and R³ and R⁴ may each bethe same or different when a and b are each an integer of 2, 3 or 4; andn is an integer of 2 to 5,000, which represents a degree ofpolymerization.
 22. The electrophotographic photoconductor as claimed inclaim 17, wherein said structural unit with charge transportingproperties is represented by formula (1):

wherein R¹ and R², which may be the same or different, are each an acylgroup, an alkyl group having 1 to 6 carbon atoms which may have asubstituent, or an aryl group which may have a substituent; and Ar¹,Ar², and Ar³ are each a substituted or unsubstituted arylene group. 23.The electrophotographic photoconductor as claimed in claim 22, whereinsaid structural unit (1) with charge transporting properties iscontained in an amount of 10 to 90 wt. % of the total weight of saidpolycarbonate resin.
 24. An electrophotographic photoconductorcomprising an electroconductive support, and a photoconductive layerformed thereon comprising as an effective component an aromaticpolycarbonate resin which comprises a structural unit of formula (2) anda structural unit with charge transporting properties, each of saidstructural units being contained in an amount of 5 wt. % or more of thetotal weight of said polycarbonate resin:

wherein a and b are each independently an integer of 1 to 4; and R³ andR⁴ are each independently a halogen atom, an alkyl group having 1 to 6carbon atoms, which may have a substituent, an alkoxyl group having 1 to6 carbon atoms, which may have a substituent, or an aryl group which mayhave a substituent, and R³ and R⁴ may each be the same or different whena and b are each an integer of 2, 3 or 4; wherein said aromaticpolycarbonate resin comprises a repeat unit of formula (3):

wherein R¹ and R², which may be the same or different, are each an acylgroup, an alkyl group having 1 to 6 carbon atoms which may have asubstituent, or an aryl group which may have a substituent; Ar¹, Ar²,and Ar³ are each a substituted or unsubstituted arylene group; a and bare each independently an integer of 1 to 4; R³ and R⁴ are eachindependently a halogen atom, an alkyl group having 1 to 6 carbon atoms,which may have a substituent, an alkoxyl group having 1 to 6 carbonatoms, which may have a substituent, or an aryl group which may have asubstituent, and R³ and R⁴ may each be the same or different when a andb are each an integer of 2, 3 or 4; and n is an integer of 2 to 5,000,which represents a degree of polymerization.
 25. An electrophotographicimage forming method comprising: charging the surface of aphotoconductor, exposing the charged surface of said photoconductor to alight image corresponding to an original image to be reproduced, therebyforming a latent electrostatic image on said photoconductor, developingsaid latent electrostatic image to a visible image, transferring saidvisible image to an image receiving member, cleaning the surface of saidphotoconductor, and quenching the residual potential on the surface ofsaid photoconductor, wherein said photoconductor comprises anelectroconductive support, and a photoconductive layer formed thereoncomprising as an effective component an aromatic polycarbonate resinwhich comprises a structural unit of formula (2) and a structural unitwith charge transporting properties, each of said structural units beingcontained in an amount of 5 wt. % or more of the total weight of saidpolycarbonate resin:

wherein a and b are each independently an integer of 1 to 4; and R³ andR⁴ are each independently a halogen atom, an alkyl group having 1 to 6carbon atoms, which may have a substituent, an alkoxyl group having 1 to6 carbon atoms, which may have a substituent, or an aryl group which mayhave a substituent, and R³ and R⁴ may each be the same or different whena and b are each an integer of 2, 3 or
 4. 26. The electrophotographicimage forming method as claimed in claim 25, wherein said structuralunit with charge transporting properties is contained in an amount of 10to 90 wt. % of the total weight of said polycarbonate resin.
 27. Theelectrophotographic image forming method as claimed in claim 25, whereinsaid structural unit with charge transporting properties is representedby formula (1′):

wherein R¹¹ is a hydrogen atom, an alkyl group which may have asubstituent, or an aryl group which may have a substituent; Ar¹ and Ar²are each an arylene group which may have a substituent; and R¹² is anaryl group which may have a substituent.
 28. The electrophotographicimage forming method as claimed in claim 25, wherein said aromaticpolycarbonate resin comprises a repeat unit of formula (3′):

wherein R¹¹ is a hydrogen atom, an alkyl group which may have asubstituent, or an aryl group which may have a substituent; Ar¹ and Ar²are each an arylene group which may have a substituent; R¹² is an arylgroup which may have a substituent; a and b are each independently aninteger of 1 to 4; R³ and R⁴ are each independently a halogen atom, analkyl group having 1 to 6 carbon atoms, which may have a substituent, analkoxyl group having 1 to 6 carbon atoms, which may have a substituent,or an aryl group which may have a substituent, and R³ and R⁴ may each bethe same or different when a and b are each an integer of 2, 3 or 4; andn is an integer of 2 to 5,000, which represents a degree ofpolymerization.
 29. The electrophotographic image forming method asclaimed in claim 25, wherein said structural unit with chargetransporting properties is represented by formula (1):

wherein R¹ and R², which may be the same or different, are each an acylgroup, an alkyl group having 1 to 6 carbon atoms which may have asubstituent, or an aryl group which may have a substituent; and Ar¹,Ar², and Ar³ are each a substituted or unsubstituted arylene group. 30.The electrophotographic image forming method as claimed in claim 25,wherein said aromatic polycarbonate resin comprises a repeat unit offormula (3):

wherein R¹ and R², which may be the same or different, are each an acylgroup, an alkyl group having 1 to 6 carbon atoms which may have asubstituent, or an aryl group which may have a substituent; Ar¹, Ar²,and Ar³ are each a substituted or unsubstituted arylene group; a and bare each independently an integer of 1 to 4; R³ and R⁴ are eachindependently a halogen atom, an alkyl group having 1 to 6 carbon atoms,which may have a substituent, an alkoxyl group having 1 to 6 carbonatoms, which may have a substituent, or an aryl group which may have asubstituent, and R³ and R⁴ may each be the same or different when a andb are each an integer of 2, 3 or 4; and n is an integer of 2 to 5,000,which represents a degree of polymerization.
 31. An electrophotographicimage forming apparatus comprising: an electrophotographicphotoconductor capable of forming a latent electrostatic image thereon,charging means for charging the surface of said photoconductor, lightexposure means for exposing the charged surface of said photoconductorto a light image corresponding to an original image to be reproduced,thereby forming a latent electrostatic image on said photoconductor,development means for developing said latent electrostatic image to avisible image, image transfer means for transferring said visible imageto an image receiving member, cleaning means for cleaning the surface ofsaid photoconductor, and quenching means for quenching the residualpotential on the surface of said photoconductor, wherein saidelectrophotographic photoconductor comprises an electroconductivesupport, and a photoconductive layer formed thereon comprising as aneffective component an aromatic polycarbonate resin which comprises astructural unit of formula (2) and a structural unit with chargetransporting properties, each of said structural units being containedin an amount of 5 wt. % or more of the total weight of saidpolycarbonate resin:

wherein a and b are each independently an integer of 1 to 4; and R³ andR⁴ are each independently a halogen atom, an alkyl group having 1 to 6carbon atoms, which may have a substituent, an alkoxyl group having 1 to6 carbon atoms, which may have a substituent, or an aryl group which mayhave a substituent, and R³ and R⁴ may each be the same or different whena and b are each an integer of 2, 3 or 4; wherein said aromaticpolycarbonate resin comprises a repeat unit of formula (3′):

wherein R¹¹ is a hydrogen atom, an alkyl group which may have asubstituent, or an aryl group which may have a substituent; Ar¹ and Ar²are each an arylene group which may have a substituent; R¹² is an arylgroup which may have a substituent; a and b are each independently aninteger of 1 to 4; R³ and R⁴ are each independently a halogen atom, analkyl group having 1 to 6 carbon atoms, which may have a substituent, analkoxyl group having 1 to 6 carbon atoms, which may have a substituent,or an aryl group which may have a substituent, and R³ and R⁴ may each bethe same or different when a and b are each an integer of 2, 3 or 4; andn is an integer of 2 to 5,000, which represents a degree ofpolymerization.
 32. The electrophotographic image forming apparatus asclaimed in claim 31, wherein said structural unit with chargetransporting properties is contained in an amount of 10 to 90 wt. % ofthe total weight of said polycarbonate resin.
 33. Theelectrophotographic image forming apparatus as claimed in claim 31,wherein said structural unit with charge transporting properties isrepresented by formula (1′):

wherein R¹¹ is a hydrogen atom, an alkyl group which may have asubstituent, or an aryl group which may have a substituent; Ar¹ and Ar²are each an arylene group which may have a substituent; R¹² is an arylgroup which may have a substituent.
 34. (Canceled):
 35. Theelectrophotographic image forming apparatus as claimed in claim 31,wherein said structural unit with charge transporting properties isrepresented by formula (1):

wherein R¹ and R², which may be the same or different, are each an acylgroup, an alkyl group having 1 to 6 carbon atoms which may have asubstituent, or an aryl group which may have a substituent; and Ar¹,Ar², and Ar³ are each a substituted or unsubstituted arylene group. 36.An electrophotographic image forming apparatus comprising: anelectrophotographic photoconductor capable of forming a latentelectrostatic image thereon, charging means for charging the surface ofsaid photoconductor, light exposure means for exposing the chargedsurface of said photoconductor to a light image corresponding to anoriginal image to be reproduced, thereby forming a latent electrostaticimage on said photoconductor, development means for developing saidlatent electrostatic image to a visible image, image transfer means fortransferring said visible image to an image receiving member, cleaningmeans for cleaning the surface of said photoconductor, and quenchingmeans for quenching the residual potential on the surface of saidphotoconductor, wherein said electrophotographic photoconductorcomprises an electroconductive support, and a photoconductive layerformed thereon comprising as an effective component an aromaticpolycarbonate resin which comprises a structural unit of formula (2) anda structural unit with charge transporting properties, each of saidstructural units being contained in an amount of 5 wt. % or more of thetotal weight of said polycarbonate resin:

wherein a and b are each independently an integer of 1 to 4; and R³ andR⁴ are each independently a halogen atom an alkyl group having 1 to 6carbon atoms which may have a substituent, an alkoxyl group having 1 to6 carbon atoms, which may have a substituent, or an aryl group which mayhave a substituent, and R³ and R⁴ may each be the same or different whena and b are each an integer of 2, 3 or 4; wherein said aromaticpolycarbonate resin comprises a repeat unit of formula (3):

wherein R¹ and R², which may be the same or different, are each an acylgroup, an alkyl group having 1 to 6 carbon atoms which may have asubstituent, or an aryl group which may have a substituent; Ar¹, Ar²,and Ar³ are each a substituted or unsubstituted arylene group; a and bare each independently an integer of 1 to 4; R³ and R⁴ are eachindependently a halogen atom, an alkyl group having 1 to 6 carbon atoms,which may have a substituent, an alkoxyl group having 1 to 6 carbonatoms which may have a substituent, or an aryl group which may have asubstituent, and R³ and R⁴ may each be the same or different when a andb are each an integer of 2, 3 or 4; and n is an integer of 2 to 5,000,which represents a degree of polymerization.
 37. An electrophotographicprocess cartridge comprising an electrophotographic photoconductorcapable of forming a latent electrostatic image thereon, wherein saidphotoconductor comprises an electroconductive support, and aphotoconductive layer formed thereon comprising as an effectivecomponent an aromatic polycarbonate resin which comprises a structuralunit of formula (2) and a structural unit with charge transportingproperties, each of said structural units being contained in an amountof 5 wt. % or more of the total weight of said polycarbonate resin:

wherein a and b are each independently an integer of 1 to 4; and R³ andR⁴ are each independently a halogen atom, an alkyl group having 1 to 6carbon atoms, which may have a substituent, an alkoxyl group having 1 to6 carbon atoms, which may have a substituent, or an aryl group which mayhave a substituent, and R³ and R⁴ may each be the same or different whena and b are each an integer of 2, 3 or 4; wherein said aromaticpolycarbonate resin comprises a repeat unit of formula (3′):

wherein R¹¹ is a hydrogen atom, an alkyl group which may have asubstituent, or an aryl group which may have a substituent: Ar¹ and Ar²are each an arylene group which may have a substituent: R¹² is an arylgroup which may have a substituent: a and b are each independently aninteger of 1 to 4: R³ and R⁴ are each independently a halogen atom, analkyl group having 1 to 6 carbon atoms, which may have a substituent, analkoxyl group having 1 to 6 carbon atoms, which may have a substituent,or an aryl group which may have a substituent, and R³ and R⁴ may each bethe same or different when a and b are each an integer of 2, 3 or 4, andn is an integer of 2 to 5,000, which represents a degree ofpolymerization.
 38. The electrophotographic process cartridge as claimedin claim 37, wherein said structural unit with charge transportingproperties is contained in an amount of 10 to 90 wt. % of the totalweight of said polycarbonate resin.
 39. The electrophotographic processcartridge as claimed in claim 37, wherein said structural unit withcharge transporting properties is represented by formula (1′):

wherein R¹¹ is a hydrogen atom, an alkyl group which may have asubstituent, or an aryl group which may have a substituent; Ar¹ and Ar²are each an arylene group which may have a substituent; and R¹² is anaryl group which may have a substituent.
 40. (Canceled):
 41. Theelectrophotographic process cartridge as claimed in claim 37, whereinsaid structural unit with charge transporting properties is representedby formula (1):

wherein R¹ and R², which may be the same or different, are each an acylgroup, an alkyl group having 1 to 6 carbon atoms which may have asubstituent, or an aryl group which may have a substituent; and Ar¹,Ar², and Ar³ are each a substituted or unsubstituted arylene group. 42.An electrophotographic process cartridge comprising anelectrophotographic photoconductor capable of forming a latentelectrostatic image thereon, wherein said photoconductor comprises anelectroconductive support, and a photoconductive layer formed thereoncomprising as an effective component an aromatic polycarbonate resinwhich comprises a structural unit of formula (2) and a structural unitwith charge transporting properties, each of said structural units beingcontained in an amount of 5 wt. % or more of the total weight of saidpolycarbonate resin:

wherein a and b are each independently an integer of 1 to 4; and R³ andR⁴ are each independently a halogen atom, an alkyl group having 1 to 6carbon atoms, which may have a substituent, an alkoxyl group having 1 to6 carbon atoms, which may have a substituent, or an aryl group which mayhave a substituent, and R³ and R⁴ may each be the same or different whena and b are each an integer of 2, 3 or 4; wherein said aromaticpolycarbonate resin comprises a repeat unit of formula (3):

wherein R¹ and R², which may be the same or different, are each an acylgroup, an alkyl group having 1 to 6 carbon atoms which may have asubstituent, or an aryl group which may have a substituent; Ar¹, Ar²,and Ar³ are each a substituted or unsubstituted arylene group; a and bare each independently an integer of 1 to 4; R³ and R⁴ are eachindependently a halogen atom, an alkyl group having 1 to 6 carbon atoms,which may have a substituent, an alkoxyl group having 1 to 6 carbonatoms, which may have a substituent, or an aryl group which may have asubstituent, and R³ and R⁴ may each be the same or different when a andb are each an integer of 2, 3 or 4; and n is an integer of 2 to 5,000,which represents a degree of polymerization.